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1.	Nyholm, R., et al. (författare) EPITAXIAL SILICIDE FORMATION IN THE MG/SI(111) SYSTEM 1993 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 289:3, s. 290-296 Tidskriftsartikel (refereegranskat)abstract The silicide formation has been studied in the Mg/Si(111) system by IOW energy electron diffraction (LEED) and photoelectron spectroscopy. It has been found that an epitaxial Mg2Si silicide is responsible for the (2/3 square-root e x 2/3 square-root 3)R30-degrees reconstruction in this system. The thickness of the silicide is limited due to the very low formation temperature for this silicide. The Fermi level is positioned 0.59 +/- 0.06 eV above the valence band maximum in the Si substrate and the valence band maximum in the epitaxial silicide is positioned 0.3 +/- 0.1 eV below the Fermi level.
2.	Nyholm, R., et al. (författare) FORMATION OF SM SILICIDES ON SI(111) - COMPOSITION AND EPITAXY 1993 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 293:3, s. 254-259 Tidskriftsartikel (refereegranskat)abstract The formation of Sm silicides on Si(111) by means of solid phase epitaxy has been studied with low energy electron diffraction, Auger electron spectroscopy and photoelectron spectroscopy of the Sm 4f level and Si 2p level. A limited reaction is found to occur already at room temperature whereas at higher temperatures a strongly intermixed Sm/Si layer showing some long range order is formed. The Sm atoms of this intermixed phase are found to be completely trivalent in accordance with expectations. The intermixed layer consists of two silicides with different compositions, one of them being SmSi2-x, the other being tentatively ascribed to SmSi.
3.	Sandell, A, et al. (författare) Metalorganic Chemical Vapor Deposition of Anatase Titanium Dioxide on Si: Modifying the Interface by Pre-Oxidation. 2003 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 530:1-2, s. 63-70 Tidskriftsartikel (refereegranskat)abstract The formation of TiO2 films on clean and pre-oxidized Si(1 1 1) through chemical vapor deposition of titanium(IV) isopropoxide (TTIP) in ultra-high vacuum has been examined by synchrotron radiation photoelectron spectroscopy, X-ray absorption spectroscopy (XAS) and scanning tunneling microscopy. In both cases, TTIP deposition at 500 °C eventually results in an anatase TiO2 film with a carbon-free surface and the surface morphology of the anatase films is very similar. By using a novel way of combining photoemission and XAS data, it is demonstrated that the two situations have substantially different interfacial properties. Pre-oxidation of the surface at 500 °C passivates the surface so that the thickness of the amorphous TiSixOy interface layer decreases from 30–35 to 15–25 Å and eliminates the formation of interfacial carbon completely.
4.	Almqvist, Nils (författare) Fractal analysis of scanning probe microscopy images 1996 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 355:1-3, s. 221-228 Tidskriftsartikel (refereegranskat)abstract The accuracy and precision of several algorithms, including newly developed, for calculating the fractal dimension from scanning probe microscopy images of material surfaces are investigated. The algorithms are based on the area-perimeter method, a variance method or versions of the structure function method. The latter two methods show good correspondence to computer simulated images, with known fractal dimensions, and have successfully been applied also on real images. The results show that these two methods give reliable fractal dimensions and are well suited to describe surface roughness quantitatively.
5.	Amandusson, Helena, et al. (författare) Methanol induced hydrogen permeation through a Pd membrane 1999 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 442:2, s. 199-205 Tidskriftsartikel (refereegranskat)abstract The dehydrogenation of methanol and the subsequent permeation of hydrogen through a 25 μm thick palladium film has been studied in a catalytic membrane reactor. At the temperature studied, 350°C, the decomposition pathway for methanol on clean palladium surfaces is believed to lead to Had and a carbonaceous overlayer. The released hydrogen can either desorb or permeate the palladium membrane. During a continuous supply of methanol hydrogen permeation is reduced and, eventually, totally quenched by the growing carbon monoxide/carbon coverage. Adding oxygen in the methanol supply can balance the increasing carbonaceous coverage through the production of carbon dioxide. In such a case, it is concluded that no CO bond scission occurs. The methanol/oxygen ratio is crucial for the hydrogen permeation rate. Isotope-labelled methanol, CH3OH, CH3OD, CD3OH and CD3OD, shows that it is preferentially the methyl (or methoxy) hydrogen that permeates the membrane.
6.	Andersson, C B M, et al. (författare) Bulk and surface electronic structure of InAs(110) 1998 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 398:3, s. 395- Tidskriftsartikel (refereegranskat)abstract The InAs(110) cleavage surface has been investigated by angle-resolved photoelectron spectroscopy. A separation between the In 4d(5/2) bulk component and the valence band maximum of 16.8 eV is found to be consistent with normal emission spectra. Experimental energy band dispersions, E-i(k), for the four bulk valence bands are established along the Sigma-line of the bulk Brillouin zone. A bulk band structure calculation utilizing the augmented plane-wave method is made. The experimental and calculated E-i(k) dispersions are found to be in good agreement with each other. E-i(k(parallel to)) dispersions for two surface-related structures are established along the lines <(Gamma)over bar>-(M) over bar and (Y) over bar-(M) over bar of the surface Brillouin zone. (C) 1998 Elsevier Science B.V.
7.	Andersson, C B M, et al. (författare) Surface atomic structure of InAs((111)over-bar)2x2 and InSb((111)over-bar)2x2 studied by core level spectroscopy 1996 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 347:1-2, s. 199-206 Tidskriftsartikel (refereegranskat)abstract Surface sensitive high resolution core level spectroscopy has been applied to the molecular beam epitaxy grown InAs((111) over bar)2 x 2 and InSb((111) over bar)2 x 2 surfaces. For both systems the In 4d core level consists of one dominating component while the Group V core levels are deconvoluted into four components. This analysis is consistent with a surface model where the topmost layer consists entirely of arsenic or antimony. In this model, Group V atoms form trimers bound to Group V atoms in the first double layer, leaving a single Group V rest atom per unit cell.
8.	ANDERSSON, CBM, et al. (författare) SPUTTERED AND ANNEALED INAS(111)OVER-BAR - AN UNRECONSTRUCTED SURFACE 1994 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 307, s. 885-889 Tidskriftsartikel (refereegranskat)abstract The electronic structure of the InAs(111BAR)1 X 1 surface has been investigated by angle resolved photoelectron spectroscopy along the symmetry lines GAMMAKBAR, GAMMAMBAR, and GAMMAMBAR of the surface Brillouin zone. The bulk valence band structure was calculated using a combination of the linear augmented plane-wave method and the relativistic augmented plane-wave method. We have projected the theoretical bulk band structure onto the surface Brillouin zone to separate surface states from surface resonances. Two surface related structures, S1 and S2, have been observed and their E(i)(k(parallel-to)) dispersions are established. Both S1 and S2 show the symmetry of the 1 X 1 surface Brillouin zone, which is consistent with the observed 1 X 1 LEED pattern. We identify S1 as the As-derived dangling bond state, and S2 is associated with the backbonds connecting the As atoms in the surface layer with the underlying In layer.
9.	BADZIAG, P (författare) ALPHA-SIC(0001)ROOT-3XROOT-3 SURFACE, POSSIBLE MODELS FOR THE RECONSTRUCTION 1995 Ingår i: Surface Science. - : ELSEVIER SCIENCE BV. - 0039-6028 .- 1879-2758. ; 337:1-2, s. 1-7 Tidskriftsartikel (refereegranskat)abstract The paper presents an analysis of the energetics of a few possible candidates for the structural model of the root 3 x root 30 degrees reconstruction of the alpha-SiC(0001) surface. The analysis is based on the semi-empirical, self-consistent, quantum mechanical cluster calculations of MNDO type (AMI parametrization). Models allowing clean stoichiometric, Si rich and C rich as well as hydrogenated surfaces were tested. The results indicate that, unlike in most cases with semiconductor surfaces, here, hydrogenation of the surface facilitates the reconstruction instead of lifting it. The most favourable model for the reconstruction from the calculated surface energy point of view is the one where hydrogenated triangles of C atoms saturate the surface silicon dangling bonds. The structure resembles that of cyclopropane with three of the C-H bonds substituted by the C-Si bonds.
10.	Badziag, P (författare) Can hydrogen stabilize the alpha-SiC(0001)root 3x root 3 surface? 1996 Ingår i: Surface Science. - : ELSEVIER SCIENCE BV. - 0039-6028 .- 1879-2758. ; 352, s. 396-400 Tidskriftsartikel (refereegranskat)abstract The paper presents an analysis of the energetics of a few possible candidates for the structural model of the root 3 X root 3 R30 degrees reconstruction of the alpha-SiC(0001) surface. The analysis is based on the semi-empirical, self-consistent, quantum-mechanical cluster calculations of MNDO-type (AM1 parametrization). Clean stoichiometric, Si rich and C rich surface structures as well as surfaces saturated by hydrogen and the hydroxyl groups are examined and particular care is applied when comparing energies of the structures with different stoichiometries. The results confirm the claim that the most favorable model for the reconstruction is here the one where hydrogenated triangles of C atoms saturate the surface silicon dangling bonds. Moreover, the calculated energies indicate that the reconstructed surface is a result of the desorption of SiO from the 1 X 1 surface originally saturated by hydroxyl groups.
11.	Baudin, Micael, et al. (författare) A molecular dynamics study of MgO(111) slabs 1997 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 375:2-3, s. 374-384 Tidskriftsartikel (refereegranskat)abstract Constant stress - constant temperature molecular dynamics simulations are reported for 30 Angstrom thick crystalline MgO (111) slabs with 2-D periodicity in the temperature range 10-1100 K. The 10 K run was 3.75 ps, the 300 K run was 41.25 ps while the others were 11.25 ps. The shell-model potential was used and the long-range interaction was taken into account with the 2-D Ewald summation technique. Two different models have been used in order to achieve the necessary charge compensation for the polar (111) surface. The relaxation of the surface structure and its temperature dependence have been investigated and compared with bulk MgO. The average coordination number in the surface layer and the surface energy are presented. The dynamics in the slab system is presented in terms of atomic mean-square displacements and vibrational density-of-states curves as a function of depth from the surface. (C) 1997 Elsevier Science B.V.
12.	Baudin, M., et al. (författare) Dynamics, structure and energetics of the (111), (011) and (001) surfaces of ceria 2000 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 468:03-jan, s. 51-61 Tidskriftsartikel (refereegranskat)abstract Molecular dynamics simulations for 20-30 Angstrom thick CeO2 slabs with 2-D periodicity are presented. The three low-index surfaces investigated are(lll), (011) and (001). The simulations were performed within a constant-temperature-constant-pressure ensemble and used the shell-model to describe polarizability. All simulation runs were performed at atmospheric pressure and in the temperature range 10-1100 K. For all three surfaces at both 300 and 1100 K, we find that the surface m.s. displacements are generally larger for the oxide ions than for the cations and that the out-of-plane surface motion is usually larger than the in-plane surface motion. At room temperature, the oxygen m.s. displacements at the (Ill)surface are a factor 1.2 larger than in the bulk, a factor 1.6 for the (011) surface and approximately five times larger at the metastable (001) surface compared to the bulk. The effect of the presence of a surface on the ion dynamics [and on the structure for (011)] persists all the way to the slab centres. even for these rather thick slabs. Our simulations for the polar (001) surface demonstrate that the relative stabilities of different faces and surface terminations can change with temperature, and that it may not always be meaningful to consider one specific user-prepared termination as superior to the others.
13.	Baudin, M., et al. (författare) Metal oxide surface dynamics from molecular dynamics simulations : the alpha-Al2O3(0001) surface 2001 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 474:03-jan, s. 107-113 Tidskriftsartikel (refereegranskat)abstract Constant-stress, constant-temperature (10, 300 and 700 K) molecular dynamics simulations were carried out with shell-model potentials for an infinite crystalline A-terminated alpha -Al2O3(000 1) slab of similar to 25 Angstrom thickness. The surface undergoes considerable relaxation at 10 K, but exhibits ordered surface structures at all three temperatures. The relaxation causes the (0 0 0 1) surface at 10 K to appear oxygen-terminated. The ionic motion within the central and surface regions of the slab system has been analysed in terms of mean-square displacements. At room temperature the (u(2))(surface)/(u(2))(bulk) ratio for the Al ions is approximate to2.5 and when only the out-of-plane surface motion is considered the ratio is as large as approximate to3.5. The O ion motion at the surface is slightly smaller than that of the cations.
14.	Bjorkqvist, M, et al. (författare) Nitride formation and dangling-bond passivation on Si(111)-(7x7) with NH3 1997 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 394:1-3, s. L155-L161 Tidskriftsartikel (refereegranskat)abstract Thermal nitridation of the Si(111)-(7 x 7) reconstructed surface with ammonia has been investigated using scanning tunneling microscopy (STM). True nitride formation in the form of ring-like structures as in stoichiometric silicon nitride (Si3N4) was observed at imperfections on the surface, which otherwise preserved the characteristics of the (7 x 7) reconstruction. However, the ratio of reacted adatoms in the reconstruction never exceeded similar to 50%, indicative of a frustrated saturation behavior for the adatom dangling bonds in the Si(111)-(7 x 7)-NH3 reaction system. (C) 1997 Elsevier Science B.V.
15.	CHAKARIAN, V, et al. (författare) THE ADSORPTION OF I2 ON SI(111)-7X7 STUDIED BY SOFT-X-RAY PHOTOEMISSION 1993 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 296:3, s. 383-392 Tidskriftsartikel (refereegranskat)abstract The adsorption Of I2 on Si(111)-7 x 7 at room temperature is studied with soft X-ray photoelectron spectroscopy. I2 adsorbs dissociatively, forming a mixture of SiI, SiI2 and SiI3 moieties, of which SiI dominates. The Fermi level is pinned near mid-gap, moving slightly towards the conduction band as the I coverage increases. The surface work function increases monotonically with I coverage. The I 4d core-level displays a single chemical state, which decreases in binding energy with increasing coverage. Analysis of the Si 2p core-level spectra shows that the adsorption proceeds first by attachment of I to the dangling bonds of the 7 x 7 unit cell and that, at saturation, 1.57 +/- 0.05 ML of I atoms are adsorbed in 1.10 +/- 0.02 ML of SiI(x) groups. These results indicate that substrate Si-Si bonds are broken by reaction with I2. The total I coverage is limited, however, by the availability Of surface dangling bonds that are required to initiate the dissociation Of I2 molecules.
16.	CHAKAROV, DV, et al. (författare) PHOTOSTIMULATED DESORPTION OF METAL ADATOMS - POTASSIUM ON GRAPHITE 1994 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 311:3, s. L724-L730 Tidskriftsartikel (refereegranskat)abstract Photodesorption is observed of single K atoms from a graphite surface covered with less than 1 monolayer of potassium. The desorption cross section has a threshold at homegaBAR almost-equal-to 3 eV and a maximum at homega(max)BAR almost-equal-to 4.9 eV. Polarization measurements indicate a substrate-mediated mechanism. The coverage dependence suggests that only the ionic 2D, K-phase is photoactive. The proposed mechanism includes attachment of hot electrons, photoexcited in the bulk, to the K4s adsorbate resonance of energy E(res). The band structure of graphite causes a narrow energy distribution of hot electrons, which yields homega(max)BAR almost-equal-to 2E(res).
17.	Chirita, Valeriu, et al. (författare) Reptation : a mechanism for cluster migration on (111) face-centered-cubic metal surfaces 1999 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 436:1-3, s. L641-L647 Tidskriftsartikel (refereegranskat)abstract Embedded-atom molecular-dynamics simulations were used to follow the diffusion dynamics of compact platinum clusters with up to 19 atoms on Pt(lll). The results reveal a cluster diffusion mechanism on (111) face-centered-cubic (fcc) surfaces involving successive shear translations of adjacent subcluster regions giving rise to reptation, a snake-like gliding motion. We show that for compact clusters with <7 atoms, this mechanism competes energetically with that of island diffusion through concerted motion. However, for cluster sizes of between 8 and similar or equal to 20 atoms, reptation becomes energetically favorable, especially for elongated clusters. Reptation is also shown to be an important migration mechanism for fractal (randomly ramified) and dendritic (symmetrically branched) islands. (C) 1999 Elsevier Science B.V. All rights reserved.
18.	Dannetun, Helen, 1957-, et al. (författare) Dehydrogenation of acetylene and ethylene studied on clean and oxygen covered palladium surfaces 1986 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 173, s. 148- Tidskriftsartikel (refereegranskat)abstract The interaction of acetylene and ethylene with a clean and oxygen covered Pd surface has been studied at a temperature of 473 K. The measurements were performed on a hydrogen sensitive Pd-MOS structure making it possible to obtain direct information on the dissociation of both hydrogen and oxygen containing species on a palladium surface. Desorption studies were also performed as well as ultraviolet photoelectron spectroscopy and work function measurements. The studies show that both acetylene and ethylene adsorb dissociatively at this temperature leaving mainly carbon on the surface. When an oxygen covered Pd surface is exposed to C2H2 or C2H4 carbon dioxide and water will be formed and desorb until the surface is oxygen free. In the case of acetylene the presence of preadsorbed oxygen does not block or prevent the C2H2 dissociation on the surface. For C2H4, a large preadsorbed oxygen coverage ( 0.45) will have an impeding effect on the dissociation. The CO2 desorption is oxygen coverage dependent contrary to the H2O desorption. This is due to the fact that hydrogen has a large lateral mobility on the surface while carbon has not. Both the CO2 and H2O reactions are, however, due to the same type of mechanisms.
19.	Dannetun, Helen, 1957-, et al. (författare) Reactions between hydrocarbon and an oxygen covered palladium surface 1988 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 193, s. 109- Tidskriftsartikel (refereegranskat)abstract Isothermic desorption studies where an oxygen covered polycrystalline Pd surface (T = 325–575 K) is exposed to small unsaturated hydrocarbons have been performed. The studied gases were acetylene, propene, propadiene, propyne, butene, butadiene, butyne, and also for comparison hydrogen. Electron energy loss spectroscopy (EELS) was available for adsorbate studies and a hydrogen sensitive Pd-MOS structure was used as a sample. The temperature limit for total dissociation is observed to decrease slightly for an oxygen covered surface compared to the clean surface. On an oxygen covered surface the dissociation is complete above 400 K and the reaction products are H2O, CO2, and adsorbed C. Varying the adsorption temperature, the carbon dioxide production is not detectable at room temperature, where all carbon is adsorbed and only water is formed, but increases to reach a constant level above 475 K. For temperatures above 400 K the licking coefficient is close to unity and there is no blocking due to preadsorbed oxygen (as there is for H2). Both the water and carbon dioxide formations are of Langmuir-Hinshelwood type but while the H2O desorption rate is found to depend only on impinging hydrocarbon flux the CO2 desorption rate depends also on the oxygen coverage.
20.	Dannetun, Helen, 1957-, et al. (författare) The H2-O2 reaction on palladium studied over a large pressure range : Independence of the microscopic sticking coefficients on surface condition 1985 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 152/153, s. 559- Tidskriftsartikel (refereegranskat)abstract We have studied the H2---O2 reaction on Pd over a large pressure range by letting the reaction take place on the Pd gate of a Pd-MOS structure. By measuring shifts in the capacitance versus voltage (C(V)) curve of the structure, the variation of the “free” hydrogen atom concentration can be monitored during the reaction. By combining these results with surface potential measurements and with photoelectron spectroscopy, we find a critical ratio of 0.4 where the surface turns from being oxygen dominated to being hydrogen dominated. The critical ratio is independent of the absolute pressures and of surface condition and shows no significant temperature dependence in the temperature range 50–200°C. This implies that hydrogen and oxygen have similar sticking coefficients at both clean and technical Pd surfaces. The conclusion is drawn that hydrogen (and oxygen) dissociation on Pd is a property of the Pd atom or cluster of Pd atoms and is not critically dependent on any long-range order parameter such as the surface electronic density of states.
21.	Dannetun, Helen, 1957-, et al. (författare) The study of alcohol induced hydrogen permeation in a catalytic membrane reactor 1996 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 357, s. 804-808 Tidskriftsartikel (refereegranskat)abstract We have studied dehydrogenation and subsequent permeation of hydrogen from some small alcohols and hydrocarbons over a 20 μm thin Pd membrane at temperatures between 523 and 623 K. It is only for the smaller alcohols that significant amounts of hydrogen permeate the membrane. An addition of oxygen in the alcohol supply is needed to prevent a slow quenching of the permeation. The ratio of oxygen to alcohol is critical. For the right balance between methanol and oxygen permeation is very effective, and comparable to permeation caused by pure hydrogen. Studies of CH3OD and C2H5OD further show that the permeation is dependent on the hydrogen origin, i.e. the methyl and hydroxyl hydrogen have different reaction pathways and permeation probabilities.
22.	Edwards, NV, et al. (författare) Real-time assessment of selected surface preparation regimens for 4H-SiC surfaces using spectroscopic ellipsometry 2000 Ingår i: Surface Science. - : Elsevier. - 0039-6028 .- 1879-2758. ; 464:1, s. L703-L707 Tidskriftsartikel (refereegranskat)abstract Spectroscopic ellipsometry (SE) was used to assess the removal of overlayer material from 4H-SiC (0001) and (0001) [Si- and C-face] surfaces in real time and, in particular, the critical final step of an otherwise standard RCA cleaning regimen commonly used to prepare SiC surfaces for contact formation. The treatments selected [buffered hydrofluoric acid (HF), concentrated HF, and dilute HF] removed 4-40 Angstrom of effective SiO2 overlayer thickness from these surfaces. The concentrated HF treatment yielded the best surface, i.e. that with the most abrupt transition region between bulk and surface and with the most oxide material removed. A fourth treatment regimen (sequential application of methanol, water, and 5% HF in methanol) was also developed for comparison with the full RCA clean. (C) 2000 Elsevier Science B.V. All rights reserved.
23.	Eriksson, Mats, 1963-, et al. (författare) Spillover of hydrogen, oxygen and carbon monoxide in oxidation reactions on SiO2 supported Pd 1994 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 311:1-2, s. 139-152 Tidskriftsartikel (refereegranskat)abstract Oxidation of H2 and CO on large, oxygen preexposed Pd islands supported on SiO2, has been investigated in the temperature range 323 ⩽, T ⩽ 523 K. The results have been compared with the corresponding reactions on a polycrystalline Pd film. A maximum reactive sticking coefficient of 0.9 for H2 and an initial sticking coefficient for O2 of 0.8 on both structures is concluded. The maximum reactive sticking coefficient for CO is 0.85 on the film and apparently larger than unity on the island structure. The results obtained from the island structure can be rationalized if O2 and H2 dissociate on the Pd islands and have the possibility to spillover onto the oxide, while CO adsorbs and reacts both on the Pd islands and on the oxide. Spillover of oxygen occurs in a precursor state and is irreversible with an apparent activation energy of 0.1 eV for the forward reaction.
24.	Eriksson, Mats, 1963-, et al. (författare) The catalytic oxidation of CO on polycrystalline Pd: Experiments and kinetic modelling 1998 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 412/413, s. 430-440 Tidskriftsartikel (refereegranskat)abstract The catalytic oxidation of CO on a thin, polycrystalline Pd film has been studied. Even though the Pd film is expected to be dominated by (111) facets, some distinct differences compared to single crystalline Pd(111) are observed. A kinetic model for the CO oxidation reaction is presented. It gives good agreement with experiments, both in terms of CO2 reaction probability and CO coverage during reaction conditions. The model assumes a random distribution of the adsorbates, an activation energy for the reaction that decreases with increasing CO coverage, as well as a CO sticking coefficient that in a temperature dependent fashion depends on the oxygen coverage. Single crystal data available from the literature (initial sticking coefficients and heats of adsorption) were mainly used as input parameters. Thus, the model might also be a useful starting point when modeling the catalytic oxidation of CO on single crystal surfaces.
25.	Fahlman, Mats, et al. (författare) Surfaces and interfaces in polymer-based electronics 2002 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 500:1-3, s. 904-922 Tidskriftsartikel (refereegranskat)abstract Research on electronics applications such as light-emitting devices for flat-panel displays, transistors, sensors and even solid state lasers based on conducting polymers is presently under way and in some cases has reached the stage of prototype production. The mechanisms for charge injection and conduction in these materials are being studied, as are the physics of luminescence and its quenching. Lately, research into controlling film morphology through self-organizing techniques also has gained interest. Though the present interest in conducting polymers mainly concerns the pristine semiconducting state, doped conducting polymers are also studied for potential use in many applications. In this paper, we present an overview of some of the central issues in surface and interface science in the field, as well as provide our view on what may lie ahead in the future. Specifically, the importance of metal/polymer, polymer/metal and polymer/polymer interfaces is addressed. We illustrate these using polymer-based light-emitting devices, though the same type of issues appear in other polymer-based applications such as transistors and solar cells. © 2001 Elsevier Science B.V. All rights reserved.
26.	Fornander, H., et al. (författare) A comparison of the CO and D2 oxidation reactions on Pd supported on MgO(100), MgO(110) and MgO(111) 1999 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 440:3, s. 375-386 Tidskriftsartikel (refereegranskat)abstract Oxidation of D2 and CO on oxygen pre-exposed 200 nm thick Pd films, epitaxially grown on MgO(100), MgO(110) and MgO(111), has been investigated in the temperature range 100–300°C. Oxygen initial sticking coefficients have been determined to be close to 1 for the 100 and 110 films, and around 0.8 for the 111 film. The sticking coefficient and reactive sticking coefficient for CO oxidation on Pd/MgO(100) is also close to 1, and the maximum reactive sticking coefficient for hydrogen oxidation is determined to be around 0.9 at temperatures above 200°C. It is shown that the reactivities for the different surfaces vary strongly with surface and oxygen coverage, and the consequence of this for supported particle catalysts is pointed out.
27.	Fornander, H., et al. (författare) Structural effects of supported Pd particles in D2 and CO oxidation experiments 1999 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 441:2-3, s. 479-492 Tidskriftsartikel (refereegranskat)abstract In the temperature range 100–300°C, isothermic D2 and CO titration experiments have been performed on oxygen pre-exposed 1.5, 4, 20 and 200 nm thick Pd films, epitaxially cube-on-cube grown on MgO(100). The oxygen pre-exposures varied from 0.2 to 150 L. The three thinnest films consisted of faceted particles, mainly bounded by Pd(111) and Pd(100) surfaces, while the 200 nm sample was a continuous, flat Pd(100) film with atomic steps. Atomic force microscopy demonstrated that the titration experiment did not affect the structure of the (large) Pd particles in the 20 nm film. The reaction behavior of the 1.5 nm film can be understood by assuming that the film consists of (111)-bounded Pd particles, where O2 and D2 dissociate and spill over to the oxide support, whereas CO adsorbs and reacts both on the Pd and on the oxide. The CO oxidation thus occurs in parallel on Pd and on MgO, while the D2 oxidation is sequential, first occurring on the Pd and then on the MgO. To explain the D2O desorption curves for the 4 and 20 nm films, spillover to the MgO support as well as reactions on the Pd(111) and Pd(100) facets have to be taken into account. The greater the oxygen pre-exposure, the higher the probability that the D2 molecules dissociate primarily on the Pd(111) surfaces.
28.	Giovanelli, L., et al. (författare) Synchrotron radiation photoelectron spectroscopy study of Pb-Pc thin films on InSb(100)-(4x2)/c(8x2) 2001 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 486:02-jan, s. 55-64 Tidskriftsartikel (refereegranskat)abstract The electronic properties and the thermal stability of a thin film of lead-phthalocyanine deposited on the InSb(100)-(4 x 2)/c(8 x 2) surface were studied by synchrotron radiation core level and valence band photoelectron spectroscopy. The interaction between the overlayer and the substrate was determined by analyzing the photoemission spectra of a thin film and of a single monolayer of adsorbed molecules. Subsequently the monolayer was annealed at increasing temperatures, leading first to a gradual change of the oxidation state of the central lead atom, then to a fragmentation of the macrocycle itself.
29.	Girard, R T, et al. (författare) Electronic structure of ZnO(0001) studied by angle-resolved photoelectron spectroscopy 1997 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 373:2-3, s. 409-417 Tidskriftsartikel (refereegranskat)abstract The electronic structure of the ZnO(0001) surface was studied by angle-resolved photoelectron spectroscopy. The recorded normal emission spectra give information about the Valence band states as well as the Zn 3d states. The dispersions of the four valence bands observed in the (0001) direction were compared with theory and are in good agreement with recent calculations which consider the Zn 3d electrons as part of the valence band. The Zn 3d states are seen to separate into two groups of four and six bands, which show dispersion with k(perpendicular to). This is in agreement with theoretical results but the location of these states were not accurately predicted. The present photoemission results show that they lie around 10.5 eV below E(F). Two surface states were observed on the (0001) surface. One, at 7.5 eV binding energy, was predicted by theory and is interpreted as arising from the ''back-bondings'' of the Zn 4s-O 2p mixed bulk states. The other one at 4.5 eV below E(F), most likely Zn 4p-0 2p derived, was not predicted by theoretical calculations and this is discussed further in the text. (C) 1997 Elsevier Science B.V.
30.	Glans, P.-A., et al. (författare) Core level and valence band photoemission study of the (1 1 1) and (1¯ 1¯ 1¯) surfaces of 3C-SiC 2001 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 470:3, s. 284-292 Tidskriftsartikel (refereegranskat)abstract A core level and valence band photoemission study of thick 3C-SiC(1 1 1) and 3C-SiC(1¯ 1¯ 1¯) epilayers grown by sublimation epitaxy is reported. The as introduced samples show threefold 1×1 low-energy electron diffraction patterns. For the Si face v3 and 6v3 reconstructed surfaces develop after in situ heating to 1100 °C and 1300 °C, respectively. For the C face a 3×3 reconstruction form after heating to 980 °C. A semiconducting behavior is observed for the v3 and 3×3 reconstructed surfaces while the 6v3 reconstruction show a Fermi edge and thus a metallic-like behavior. The surface state on the v3 surface is investigated and found to have ?1 symmetry and a total band width of 0.10 eV within the first surface Brillouin zone. For the Si2p and C 1s core levels binding energies and surface shifted components are extracted and compared to earlier reported results for 6H- and 4H-SiC.
31.	GOTHELID, M, et al. (författare) ADSORPTION OF TIN ON THE GE(111)-C(2X8) SURFACE STUDIED WITH SCANNING-TUNNELING-MICROSCOPY AND PHOTOELECTRON-SPECTROSCOPY 1995 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 328:1-2, s. 80-94 Tidskriftsartikel (refereegranskat)abstract The growth and epitaxy of Sn on Ge(111) have been investigated using scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and core level photoelectron spectroscopy for coverages ranging from 0.4 monolayers (ML) to above the critical coverage at 1.6 ML. At the lowest coverage a (root 3 X root 3)R30 degrees reconstruction is formed at an annealing temperature of 250-300 degrees C while an annealing above 500 degrees C creates a dimer-adatom-stacking fault (DAS) (7 X 7) structure. In the (7 X 7) structure we argue that Sn occupies both adatom and dimer sites. A previously suggested difference in the (root 3 X root 3)R30 degrees reconstruction at different coverages could not be revealed in our STM images and it seems likely that the structure is the same both at 0.4 and 0.7 ML Sn coverage. We also report the observation of a new superstructure, a (4 X root 7) reconstruction in the submonolayer regime, which appears as a minority structure in disordered regions adjacent to a (5 X 5) DAS structure, Finally in the post-monolayer region a (3 X 2 root 3) structure, surrounded by vast areas of an amorphous tin overlayer, has been imaged by STM. As the coverage was increased, the amorphous layer completely covered the ordered (3 X 2 root 3) phase, which still could be observed in LEED. Additional room temperature deposition of Sn deteriorated the fractional order LEED spots presumably due to indiffusion of Sn from the interface as the critical coverage was surpassed.
32.	Gothelid, M, et al. (författare) Iodine reaction and passivation of the Ge(111) surface 1997 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 371:2-3, s. 264-276 Tidskriftsartikel (refereegranskat)abstract The Ge(111)-I surface has been studied at different I coverages ranging from 0.05 hit up to saturation, and different annealing temperatures, using photoelectron spectroscopy (PES) and scanning tunneling microscopy (STM). At saturation the surface is covered with I in the top site and Gel, species in the bridge site, coexisting with small islands/clusters comprising GeI2, giving a total coverage of I in GeIx species of 1.15 ML. The chemically induced shifts in the Ge 3d core level are 0.39 eV per attached I atom. The coverage determined from the I 4d core level is higher than 1.15 ML, which we explain by the presence of I not bound to Ge. Annealing at 200 degrees C decreases the iodine coverage, whereas the I 4d and Ge 3d line profiles are practically unchanged. Further heating desorbs the iodide species and restores the virgin c(2 x 8) structure.
33.	GOTHELID, M, et al. (författare) SN-INDUCED SURFACE RECONSTRUCTIONS ON THE GE(111) SURFACE STUDIED WITH SCANNING TUNNELING MICROSCOPY 1992 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 271:3, s. L357-L361 Tidskriftsartikel (refereegranskat)abstract Scanning tunneling microscopy (STM) has been used to study different Sn induced reconstructions on the Ge(111) surface; namely the (7 x 7), (5 x 5) and (square-root 3 x square-root 3)R30-degrees structures. The first two have been confirmed to be of the dimer adatom stacking fault (DAS) type with adatoms mainly being Sn. The (square-root 3 x square-root 3)R30-degrees superstructure was found at different Sn depositions. At 0.4 monolayer (ML) Sn coverage a homogeneous Sn adatom layer is adsorbed on the (1 x 1) surface in threefold sites directly over second-layer atoms (T4), while at low coverage, 0.1 ML, the top layer is a mixture of Sn and Ge atoms. We also propose the chemical identities of the different atoms seen in the STM images as related to their apparent height.
34.	Habermehl-Cwirzen, Karin, et al. (författare) An experimental study on adsorption of benzene on Co(0001) 2002 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 507, s. 57-61 Tidskriftsartikel (refereegranskat)abstract The adsorption of benzene on Co(0 0 0 1) was studied by X-ray photoelectron spectroscopy, temperature programmed desorption, low energy electron diffraction (LEED) and work function measurements. The adsorption was found to be molecular at room temperature and to saturate at a fractional coverage of 0.125 ML. With LEED a c(2root3 x 4) overlayer structure was seen. Below 220 K at high exposures a p(root7 x root7)R19degrees LEED pattern was observed corresponding to a coverage of 0.143 ML. Temperature programmed desorption measurements stated that benzene starts to decompose around 340 K to hydrogen and a hydrocarbon fragment, most likely C6H5. While the hydrogen desorbed, the hydrocarbon stayed at the surface. The desorption of molecular benzene was negligible. The activation energy for the dehydrogenation was calculated to be about 102 kJ/mol. The work function of Co(0 0 0 1) decreased by 1.3 eV upon saturation with benzene. The induced dipole moment was calculated to be 1.9 Debye/molecule.
35.	Hakansson, M C, et al. (författare) The electronic structure of In- and As-terminated InAs(001) surfaces 1997 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 374:1-3, s. 73-79 Tidskriftsartikel (refereegranskat)abstract The InAs(001) 2 x 4 and 4 x 2 surfaces have been investigated by angle-resolved photoemission. The X(3) and X(5) points were found to be located 6.0 and 2.7 eV below the valence band maximum, respectively, and the dispersion of bulk bands along the Gamma-X direction in the bulk Brillouin zone were well described by a theoretical calculation. From angle-resolved valence band spectra measured along the high symmetry directions [110] and [1(1) over bar0$], three surface induced stares were identified on both the InAs(001)4 x 2 and the InAs(001)2 x 4 surface. (C) 1997 Elsevier Science B.V.
36.	HAKANSSON, MC, et al. (författare) DIMER FORMATION AND ELECTRONIC-STRUCTURE ON THE GE(100)(2X1)-SB SURFACE 1992 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 278:1-2, s. L131-L134 Tidskriftsartikel (refereegranskat)abstract Deposition of antimony on Ge(100)2 X 1 results in a well-ordered, highly passivated surface. From a comparison between core-level data and angle-resolved photoemission data, we conclude that the observed 2 x 1 reconstruction is caused by the formation of symmetric Sb-Sb dimers on the Ge surface.
37.	Hellsing, B, et al. (författare) Photoinduced desorption of potassium atoms from graphite 1996 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 363:1-3, s. 247-251 Tidskriftsartikel (refereegranskat)abstract We present an experimental and theoretical investigation of desorption of potassium atoms from the basal plane of graphite induced by photons with energies from 2 to 6 eV. The intensity of the photon flux employed in the measurements is low, and the observed photodesorption is a single-photon, non-thermal event. At monolayer coverage the photon-energy dependence of the cross section has a maximum at 4.8 eV. The experimental observations are interpreted in terms of a hot carrier mechanism, which involves attachment of optically excited substrate hot electrons to the empty 4s state of ionized potassium, and then desorption. The theory predicts a Gaussian line shape of the photoyield versus photon energy. Fitting the model parameters to the experimental data, we determine: (i) the potential energy for Gr + K+ and Gr + K-0; and (ii) the position (2.4 eV above the Fermi level) and width (0.15 eV) of the potassium 4s resonance, which is in good agreement with independent experimental observations.
38.	Hirschauer, B., et al. (författare) Oxidation of Ce on Si(111) studied by high-resolution photoelectron spectroscopy 2000 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 464:03-feb, s. 117-122 Tidskriftsartikel (refereegranskat)abstract The Si(lll)-Ce (2x2) surface was studied by photoelectron spectroscopy during oxidation and annealing. Detailed analysis of the Si 2p core-level spectra and the Ce valence band levels shows that Ce is first oxidised and then promotes oxidation of Si at room temperature by improving the oxygen uptake of the surface. Initially, no oxidation of Si can be recorded, but at exposures of 3 L O-2 or more, SiOx and higher silicon oxides are formed. After annealing to 750 degreesC, a temperature that is generally used to oxidise Si, almost all O leaves the surface. At 1045 degreesC, the Si 2p and the Ce valence band spectra of the sample show almost the same shape as for the original Si(lll)-Ce 2x2 surface. This means that oxidation/reduction of the Si(lll)-Ce 2x2 surface is reversible.
39.	Hoffmann, F.M., et al. (författare) The activation of CO2 by potassium-promoted Ru(001) I. FT-IRAS and TDMS study of oxalate and carbonate intermediates 1994 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 316:3, s. 277-293 Tidskriftsartikel (refereegranskat)abstract The interaction of CO2 with the clean and alkali promoted Ru(001) surface has been studied with time-evolved Fourier transform-infrared reflection absorption spectroscopy (FT-IRAS) and thermal desorption mass spectrometry (TDMS). CO2 adsorbs on the clean Ru(001) surface at 85 K in a physisorbed CO2 monolayer, which desorbs undissociated at 100 K. The interaction of CO2 with a √3 × √3-R30° monolayer of potassium on Ru(001) results in the facile formation of oxalate at 85 K. Oxalate decomposes to carbonate after heating above 150 K, i.e. C2O4 → CO3 + CO. Vibrational spectra suggest, in agreement with theoretical calculations, an ionic carbonate species with D3h symmetry and the molecular plane oriented perpendicular to the surface, although alternate coordinations cannot be completely ruled out. Decomposition of the carbonate starts at 700 K and results in the simultaneous desorption of K and CO2 as major decompositions products, suggesting a reaction pathway of CO3 → CO2 + O and a K:CO3 stoichiometry of ≈1:1. The interaction of CO2 with a multilayer of potassium adsorbed on Ru(001), exhibits similar intermediates as observed for the monolayer, i.e. oxalate and carbonate. However, the overall reaction behavior is more complex and controlled by the penetration of CO2 into the potassium layer, which limits the reaction to only a few (4-5) of the topmost potassium layers. Reaction at 85 K reveals the formation of oxalate, CO2-2 and possibly CO-2 species. Annealing of the multilayer to 425 K results in the formation of carbonate, and the desorption of unreacted potassium. Vibrational spectra characterize an essentially ionic carbonate species with a preferential orientation of the molecular plane perpendicular to the surface, although the vibrational linewidths suggest imperfect ordering of the layer. Further annealing to 550 K results in a well-ordered "bilayer", containing two carbonate species with the molecular plane perpendicular (C2v, first layer) and parallel (C3v, second layer) to the surface, respectively. Decomposition of this layer at 700 K leaves a carbonate monolayer which subsequently decomposes at 750 K. The overall decomposition behavior of the multilayer is complex and is sensitive to the preparation and thickness of the potassium multilayer.
40.	Janin, Emmanuelle, et al. (författare) Adsorption and bonding of propene and 2-butenal on Pt(111) 2001 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 482, s. 83-89 Tidskriftsartikel (refereegranskat)abstract The adsorption of propene and 2-butenal on the Pt(1 1 1) surface has been studied by high resolution photoelectron spectroscopy, both in the mono-and multi-layer regime. The results obtained indicate an involvement of both aliphatic and carbonyl groups in the bonding of 2-butenal with the platinum surface in the sub-monolayer regime.
41.	Janin, E., et al. (författare) Corrosive adsorption of Sn on the Pt(110)(1 x 2) surface 2002 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 515:03-feb, s. 462-470 Tidskriftsartikel (refereegranskat)abstract Room temperature deposition of Sn on the Pt(110)(1 x 2) surface has been studied by scanning tunnelling microscopy and core level photoelectron spectroscopy. At low coverage Sri is found in three different configurations; as mobile adatoms in the valley of the missing-row reconstruction, as 1D-Pt-Sn-Pt- alloy chains forming local Pt3Sn(110)2 x 2 regions and finally as 3D alloy islands. At higher coverage these islands form a platinum rich alloy film, which is dissolved in the crystal upon annealing to 600 degreesC.
42.	Jemander, S.T., et al. (författare) STM study of the surface defects of the (v3×v3)-Sn/Si(1 1 1) surface 2001 Ingår i: Surface Science. - : Elsevier. - 0039-6028 .- 1879-2758. ; 475:1-3, s. 181-193 Tidskriftsartikel (refereegranskat)abstract The (v3×v3)-Sn/Si(1 1 1) surface has been studied with scanning tunneling microscopy (STM) and Auger electron spectroscopy, and it is found that it contains basically five different types of defects originating from substitutional atoms and vacancies. The influence the defects have on their immediate neighbourhood is investigated and found to extend to the third nearest (v3×v3) adatom neighbour. Close to some defect constellations, a very local (3×3) periodicity in the apparent height in the STM images is found. This periodicity is shown to be a linear superposition of the perturbations generated by the individual defects in the constellations. The superposition of the height modulation is accurate and linear for a wide range of tip biases, as for combinations of different types of defects. Its linearity is explained in terms of small perturbations in the surface electronic structure. We also provide an explanation why the linearity breaks down when large perturbations are probed with small tip biases.
43.	JOHANSSON, LI, et al. (författare) CORE LEVEL PHOTOEMISSION-STUDY OF CR3SI(100) 1991 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 251, s. 101-107 Tidskriftsartikel (refereegranskat)abstract High resolution photoemission studies of the core levels in Cr3Si have been carried out using synchrotron radiation. Investigations were performed both on the clean surface, cleaned in situ by sputter and annealing cycles, and after oxygen exposures. A surface shifted Si 2p component was observed on the annealed surface but no surface shifted component could be identified in the Cr 3p spectrum. The surface shift was extracted using a curve fitting procedure and found to be -0.30(5) eV. The shift expected due to the loss of coordination at the surface is found to be negative but of about half the size of the observed shift. Upon oxygen adsorption at room temperature a chemically shifted Si 2p component appeared already after an exposure of < 1 L, indicating rapid silicon oxidation, while a chemically shifted Cr 3p component could be resolved only after exposures of about 10 L. These findings are presented and discussed.
44.	Johansson, Leif, et al. (författare) Properties of the SiO2/SiC interface investigated by angle resolved studies of the Si 2p and Si 1s levels and the Si KLL Auger transitions 2003 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 529:3, s. 515-526 Tidskriftsartikel (refereegranskat)abstract Angle resolved photoemission studies of the Si 2p and Si 1s core levels and the Si KL2,3L2,3 Auger transitions from SiO2/SiC samples are reported. Most samples investigated were grown in situ on initially clean and well ordered v3 × v3 reconstructed 4H-SiC(0 0 0 1) surfaces but some samples were grown ex situ using a standard dry oxidation procedure. The results presented cover samples with total oxide thicknesses from about 5 to 118 Å. The angle resolved data show that two oxidation states only, Si+1 and Si+4, are required to explain and model recorded Si 2p, Si 1s and Si KLL spectra. The intensity variations observed in the core level components versus electron emission angle are found to be well described by a layer attenuation model for all samples when assuming a sub-oxide (Si2O) at the interface with a thickness ranging from 2.5 to 4 Å. We conclude that the sub-oxide is located at the interface and that the thickness of this layer does not increase much when the total oxide thickness is increased from about 5 to 118 Å. The SiO2 chemical shift is found to be larger in the Si 1s level than in the Si 2p level and to depend on the thickness of the oxide layer. The SiO2 shift is found to be fairly constant for oxides less than about 10 Å thick, to increase by 0.5 eV when increasing the oxide thickness to around 25 Å and then to be fairly constant for thicker oxides. An even more pronounced dependence is observed in the Si KLL transitions where a relative energy shift of 0.9 eV is determined. The relative final state relaxation energy dR(2p) is determined from the modified Auger parameter. This yields a value of dR(2p) = -1.7 eV and implies, for SiO2/SiC, a "true" chemical shift in the Si 2p level of only ˜0.4 eV for oxide layers of up to 10 Å thick. © 2003 Elsevier Science B.V. All rights reserved.
45.	Karlsson, Fredrik, 1974-, et al. (författare) Effective tuning of the charge-state of single In(Ga)As/GaAs quantum dots by below barrier band gap excitation 2003 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 532-535, s. 843-847 Tidskriftsartikel (refereegranskat)abstract The existence of a well-defined threshold energy, crucial for the charging of quantum dots (QDs), positioned between the barrier band gap and the wetting layer ground state is demonstrated. Optical excitation with energies above this threshold populates the QDs with extra electrons. The origin of the threshold is discussed in terms of acceptors in the GaAs barrier. ⌐ 2003 Elsevier Science B.V. All rights reserved.
46.	Karlsson, H S, et al. (författare) Electron accumulation at the InAs(110) cleavage surface 1998 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 402:1-3, s. 590-594 Tidskriftsartikel (refereegranskat)abstract The InAs(110) cleavage surface is studied by photoelectron spectroscopy based on an amplified short-pulse titanium:sapphire laser system in both probe-only and pump-and-probe modes. The probe-only spectra show that electrons accumulate in the conduction band at the surface as a function of time after cleavage, while the pump-and-probe spectra show a different response from the excited accumulation layer peak when using s- and p-polarized probe pulses. Moreover, no surface photovoltage is detected when the accumulation layer is optically pumped. (C) 1998 Elsevier Science B.V. All rights reserved.
47.	Karlsson, H S, et al. (författare) Electron dynamics and accumulation on the InAs(110) surface 1998 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 407:1-3, s. L687-L692 Tidskriftsartikel (refereegranskat)abstract Time- and angle-resolved pump-and-probe photoelectron spectroscopy has been used to study the electron dynamics on the InAs(110) surface. Two states, separated by similar to 0.2 eV, can be identified in the conduction band. The time evolution and energy location of these states suggest that they originate from transiently excited levels related to the InAs bulk conduction band. (C) 1998 Elsevier Science B.V. All rights reserved.
48.	KARLSSON, Ulf O, et al. (författare) ELECTRONIC-STRUCTURE OF THE HCP PHASE OF SILVER-ALUMINUM ALLOYS 1983 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 126:1-3, s. 58-65 Tidskriftsartikel (refereegranskat)
49.	Larsson, Mats, 1976-, et al. (författare) Photoluminescence study of Si/Ge quantum dots 2003 Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 532-535, s. 832-836 Tidskriftsartikel (refereegranskat)abstract Ge quantum dots embedded in Si are studied by means of photoluminescence (PL). The temperature dependent PL measurements show two different types of recombination processes related to the quantum dots. We ascribe a peak near 0.80 eV to the spatially indirect recombination in the type-II band lineup where the electron is located in the surrounding Si close to the interface and the hole in the Ge dot. Furthermore, a peak near 0.85 eV is attributed to the spatially direct recombination. We observe a transition from the spatially indirect to the spatially direct recombination as the temperature is increased. The measurements also show an up-shift of the Ge quantum dot emission energy with increasing excitation power density. The blueshift is primarily ascribed to an enhanced confinement of the electron associated with the increased band bending at the type-II Si/Ge interface at high carrier densities. Comparison is made with results, derived from measurements on uncapped samples. For these uncapped samples, no energy shifts due to excitation power or temperatures are observed in contrast to the capped samples. ⌐ 2003 Elsevier Science B.V. All rights reserved.
50.	LELAY, G, et al. (författare) STM AND SYNCHROTRON-RADIATION STUDIES OF PROTOTYPICAL METAL-SEMICONDUCTOR SYSTEMS 1994 Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 307, s. 280-294 Tidskriftsartikel (refereegranskat)abstract Since the origin of surface science noble metal/elemental semiconductor couples have been considered as ''prototypical'' systems. After three decades of research their structural and electronic properties remain an intriguing maze despite recent advances made, especially thanks to the development of the near-field microscopies and the ''tensive use of synchrotron radiation in surface crystallography and in high-resolution photoelectron spectroscopy. In the last few years, lead, as a replacement inert metal, has nearly gained the pole position in the display of exotic behaviour. This paper gives a flavour of this mystery story and highlights some puzzling questions.

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