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1.	Borgström, Magnus, et al. (författare) InAs quantum dots grown on InAlGaAs lattice matched to InP 2003 Ingår i: Journal of Crystal Growth. - 0022-0248. ; 252:4, s. 481-485 Tidskriftsartikel (refereegranskat)abstract In this paper, we present InAs quantum dots prepared on an InxAlyGa1-x-yAs surface by metal organic vapor phase epitaxy. Atomic force microscopy measurements indicate that dots grown on material with higher Al content are smaller, and that the local dot densities on step-bunched facets formed on the vicinal (0 0 1) surfaces increase. We find that these dots show luminescence at very long wavelengths, lambda(room temperature) approximate to 2.1 mum, and that the emission wavelengths are blue-shifted when the Al content is increased in the layer onto which dot material is deposited. (C) 2003 Elsevier Science B.V. All rights reserved.
2.	Borgström, Magnus, et al. (författare) Site control of InAs quantum dots on a patterned InP surface: As/P exchange reactions 2003 Ingår i: Journal of Crystal Growth. - 0022-0248. ; 248, s. 310-316 Tidskriftsartikel (refereegranskat)abstract In this paper. we present the effect of annealing temperature and annealing time on InAs site-controlled quantum dot growth. Individual InAs quantum dots formed by self-assembling have been positioned into holes, created by partial overgrowth of electron beam induced nano-carbon deposits by metal organic vapor phase epitaxy. As/P exchange reactions produce material sufficient for selective dot nucleation in the holes. Results. showing that As/P exchange reactions occur even when capping the dots with InP are presented. (C) 2002 Elsevier Science B.V. All rights reserved.
3.	Carlsson, N, et al. (författare) IMPROVED SIZE HOMOGENEITY OF INP-ON-GAINP STRANSKI-KRASTANOW ISLANDS BY GROWTH ON A THIN GAP INTERFACE LAYER 1995 Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 156:1-2, s. 23-29 Tidskriftsartikel (refereegranskat)abstract Coherent InP nano-sized islands, embedded into GaInP, have been grown by metal-organic vapour phase epitaxy using the Stranski-Krastanow growth mode. Photoluminescence, atomic force microscopy and transmission electron microscopy studies show that the insertion of a thin ∼ 4 monolayer thick GaP layer affects the critical thickness of the subsequently deposited two-dimensional InP wetting layer, increasing it from ∼ 1.5 monolayers (without an inserted GaP layer) to ∼ 2.5 monolayers (with an inserted GaP layer). We demonstrate that the inserted GaP layer affects also the island formation. The bimodal size distribution of Stranski-Krastanow islands, typical for low InP coverages, can be overcome without island coalescence by deposition on top of the thin GaP layer, where a coverage of InP of about 3.5–4.5 monolayers results in the formation of almost only the larger, fully developed, pyramidal islands. Annealing experiments at growth temperature of 580°C show that these islands (base area ≈ 40 × 50 nm2, height ≈ 10–15 nm, surface density ≈ (1−2) × 109 cm−2) are rather stable in a time-scale over several minutes before they slowly undergo an Ostwald ripening process.
4.	Ferdos, Fariba, 1966, et al. (författare) Influence of initial GaAs and AlAs cap layers on InAs quantum dots grown by molecular beam epitaxy 2003 Ingår i: Journal of Crystal Growth. - 0022-0248. ; 251:1-4, s. 145-9 Tidskriftsartikel (refereegranskat)abstract Capping of InAs quantum dots (QDs) with AlAs or GaAs causes a significant change in the structural properties of the QDs. However, there is a basic difference between these two capping materials. The GaAs capping causes a dramatic reduction of the dot density and height. AlAs capping, on the other hand, results in a partly suppressed height reduction and a higher dot density.
5.	Ferdos, Fariba, 1966, et al. (författare) Optimisation of MBE growth conditions for InAs quantum dots on (001) GaAs for 1.3 μm luminescence 2001 Ingår i: Journal of Crystal Growth. - 0022-0248. ; 227-228, s. 1140-5 Tidskriftsartikel (refereegranskat)abstract We present a study of the optimised growth conditions for InAs quantum dots (QDs) grown on GaAs substrates by solid source molecular beam epitaxy (SSMBE). Growth conditions for best luminescence intensity and linewidth were found within narrow windows of substrate temperature (500-520°C) and nominal InAs layer thickness (3.3-3.7 monolayers). The emission wavelength of such InAs QDs capped by GaAs was around 1.24 ?m. However, this is redshifted to 1.3 ?m or more by capping the InAs QDs with a thin layer of InxGa1-xAs. The results show that both In content and thickness of the capping layer can be used to tune the emission wavelength. Atomic force microscopy images show that the surface recovers to two-dimensional when depositing In0.2Ga0.8As while remaining three-dimensional when depositing In0.4Ga0.6As.
6.	Håkansson, G., et al. (författare) Ion irradiation effects during growth of Mo/V(001) superlattices by dual-target magnetron sputtering 1992 Ingår i: Journal of Crystal Growth. - 0022-0248. ; 121:3, s. 399-412 Tidskriftsartikel (refereegranskat)abstract Epitaxial (001)-oriented Mo/V superlattice films with wavelengths of ≈ 5 nm have been grown on MgO(001) substrates, kept at 700°C, by dual-target unbalanced magnetron sputter deposition in Ar discharges. Low-energy (15-250 eV) Ar ion irradiation with incident ion-to-metal flux ratio of ≈ 1 during film growth was obtained through the application of a negative potential Vs to the substrate. The effects of ion bombardment on interface roughness and mixing, resputtering rates, and defect structure were investigated using a combination of cross-sectional transmission electron microscopy (XTEM), X-ray diffraction (XRD), and simulation of XRD patterns. High-resolution XTEM images showed that the interfaces were relatively sharp for Vs ≤ 100 V while higher Vs values resulted in more diffuse interfaces indicating ion-induced intermixing. By using a kinematical model of diffraction, and comparing with experimental XRD results, it could be concluded that the intermixing increased from ≈ 0.3 nm (2 monolayers) at Vs = 15 V to & 0.9 nm (6 monolayers) at Vs = 250 V. The inhomogeneous strain showed a large increase for Vs & 50 V. This is explained by an incorporation of point defects. Coherency strain relaxation between layers is suggested to take place through the formation of edge dislocations with Burgers vector 〈110〉 by climb processes. Finally, increasing Vs also resulted in resputtering, preferentially from the V layers.
7.	Johansson, Jonas, et al. (författare) Kinetics of self-assembled island formation: Part I - Island density 2002 Ingår i: Journal of Crystal Growth. - 0022-0248. ; 234:1, s. 132-138 Tidskriftsartikel (refereegranskat)abstract We present a rate equation model for self-assembled quantum dot formation, or Stranski-Krastanow growth. The model includes a kinetically defined critical wetting layer thickness and a subsequent wetting layer decomposition. With these rate equations, total island densities can be calculated under varying deposition conditions, i.e., temperature and deposition rate.
8.	Johansson, Jonas, et al. (författare) Kinetics of self-assembled island formation: Part II - Island size 2002 Ingår i: Journal of Crystal Growth. - 0022-0248. ; 234:1, s. 139-144 Tidskriftsartikel (refereegranskat)abstract In this paper, we propose a simple and intuitive way to predict self-assembled island sizes for varying deposition conditions, i.e., temperature and deposition rate. The average island size and the modality of the size distribution (unimodal with large or small islands, or bimodal) is calculated via materials balancing over a total island density (known by experiments or from nucleation calculations). We also find that there is a density interval in which the size distribution is bimodal. The width of this interval increases with the total amount of material in the islands. The borders of the interval change with the sizes of the small and large islands, which can also change the interval width. (C) 2002 Elsevier Science B.V. All rights reserved.
9.	Petfordlong, Amanda K., et al. (författare) On the growth of small crystals of Cd, Zn, Pt and Rh during electron microscope observations 1987 Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 80:2, s. 218-224 Tidskriftsartikel (refereegranskat)abstract The growth of small supported metal crystals under the influence of an electron beam has been studied in real-time using a 400 keV ultra-high-resolution electron microscope. Samples of Pt, Rh, Cd and Zn supported on amorphous C or Si films were prepared ex situ and crystal growth in situ was recorded directly using a TV imaging/video system attached to the microscope. The different types of observed crystal growth are reported: the fcc metals (Pt and Rh) grow by coalescence, or by the addition of atoms along the particle surface followed by structural rearrangements which result in approximately spherical particles. The hcp metals (Cd and Zn) grow in the form of long rafts along the surface of the substrate film.
10.	Sass, T, et al. (författare) Strain in GaP/GaAs and GaAs/GaP resonant tunnelling heterostructures 2003 Ingår i: Journal of Crystal Growth. - 0022-0248. ; 248, s. 375-379 Tidskriftsartikel (refereegranskat)abstract We studied the morphology of GaP/(001)GaAs and GaAs/(001)GaP heterostructures grown by metal-organic vapour-phase epitaxy and found wire-like surface undulations elongated in the [110] direction. We attribute this elongation to anisotropic lateral growth rates in the [110] and [110] directions, which are due to a different roughness of monolayer surface steps. In III-V materials grown by molecular beam epitaxy. such surface corrugations are usually elongated in [110]. We explain this difference by the two growth methods having inverted ratios of lateral growth rates in [110] and [110]. Resonant tunnelling diodes fabricated from the GaP/GaAs heterostructures showed very symmetric I-V characteristics. Their peak-to-valley ratio was limited to 2. most probably due to the corrugation of the GaP barriers. (C) 2002 Elsevier Science B.V. All rights reserved.
11.	Baskar, K., et al. (författare) Surface morphology and localised states of GaInNAs single quantum wells grown by MOVPE 2003 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 248, s. 431-436 Tidskriftsartikel (refereegranskat)abstract GaInNAs/GaAs single quantum wells (QWs) have been grown by metalorganic vapour phase epitaxy (MOVPE). The surface morphology has been studied by atomic force microscopy (AFM). The density of pits observed on the surface of QW structures was found to depend on the growth temperature and dimethylhydrazine (DMHy) flow. Cross-sectional AFM image showed the presence of defects at the interface of GaInNAs/GaAs. The low temperature photoluminescence characteristics of the QWs as a function of growth temperature. DMHy flow and density of surface pits have been discussed. The origin of pit formation is addressed based on the pyrolysis products present during the growth of QWs. The results suggest that higher growth temperature maybe desirable to obtain good quality GaInNAs QWS.
12.	Bertone, Daniele, et al. (författare) Etching of InP-based MQW laser structure in a MOCVD reactor by chlorinated compounds 1998 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 195:1-4, s. 624-629 Tidskriftsartikel (refereegranskat)abstract Four different chlorinated compounds: 2-chloropropane, dichloromethane, chloroform and carbon tetrachloride have been used to etch InGaAsP/InP MQW laser structures partially masked. Etching experiments were performed in a home-made LP-MOCVD reactor with argon or argon + hydrogen as carrier gas, using phosphine (PH3) or tertiarybutylphosphine (TBP) to prevent thermal decomposition. The etching temperature as well as the chlorinated compound flow were varied to obtain the best trade-off between etch rate and surface morphology. The optimized experimental conditions were applied to etch mesa stripes in a SCH-MQW laser structure, for the first time to our knowledge, followed by lateral InP : Fe regrowth in the same step. Threshold current as low as 4 mA (best value)-6 mA (typical value) and differential quantum efficiency higher than 20% for SI-BM MQW laser have been achieved.
13.	Buyanova, Irina, 1960-, et al. (författare) Intrinsic modulation doping in InP-based structures : properties relevant to device applications 1999 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 201-202, s. 786-789 Tidskriftsartikel (refereegranskat)abstract In this work we study device-relevant issues, such as doping efficiency and thermal stability, of recently proposed intrinsic modulation doping approach where intrinsic defects (PIn antisites) are used as a carrier source instead of impurity dopants. The InP/InGaAs heterostructure designed to resemble high electron mobility transistor (HEMT) structures, where all the layers were grown at a normal growth temperature 480°C except for the top InP layer which was grown at 265°C, was used as a prototype device. A comparison between the intrinsically doped structure with extrinsically doped HEMTs, which have an identical design except that the top InP layer was instead Si-doped and was grown at 480°C, reveals a high efficiency of the intrinsic doping. The thermal stability of the intrinsically doped HEMT is examined by annealing at temperatures 400-500°C relevant to possible processing steps needed in device fabrication. The observed severe reduction of the carrier concentration after annealing performed without phosphorous gas protection is attributed to the known instability of an InP surface at T>400°C. Thermal stability of the intrinsically doped HEMT is shown to be improved by using an InP cap layer grown at 480°C.
14.	Carlsson, Mats, et al. (författare) Synthesis and characterisation of boron carbide whiskers and thin elongated platelets 2002 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 236:1-3, s. 466-476 Tidskriftsartikel (refereegranskat)
15.	Cerreta, M.K., et al. (författare) Contact nuclei formation in aqueous dextrose solutions 1990 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 102:4, s. 869-876 Tidskriftsartikel (refereegranskat)abstract A laser Raman microprobe was used in situ to observe the growth of alpha dextrose monohydrate on alpha anhydrous dextrose crystals. The Raman spectra indicate growth of the monohydrate below 28.1°C, but the presence of only the anhydrous form above 40.5°C. Contact nucleation experiments with parent anhydrous crystals yielded only monohydrate nuclei below 28.1°C, while contacts in solutions between 34.5 and 41.0°C produced both crystalline forms, and contacts in solutions above 43.5°C produced only anhydrous nuclei. The inability of the monohydrate to grow on anhydrous crystals in the same solution that forms the two crystalline phases with a single contact precludes a simple attrition mechanism of nuclei formation. For the same reason, the hypothetical mechanism involving parent crystal stabilization of pre-crystalline clusters, allowing the clusters to grow into nuclei, is also contradicted. A third, mechanism, which may be a combination of the two, is believed to apply.
16.	Cerreta, M.K., et al. (författare) The structure of aqueous solutions of some dihydrogen orthophosphates by laser Raman spectroscopy 1987 Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 84:4, s. 577-588 Tidskriftsartikel (refereegranskat)abstract Powdered crystals and pure, aqueous solutions of ammonium, sodium, and potassium dihydrogen orthophosphates in concentrations ranging from 0.01M to supersaturated were investigated at 30°C using laser Raman spectroscopy between 700 and 1350 cm-1. With increasing solute concentration, the peak position of the 875 cm-1 P-(OH)2 symmetric strech band increased. Extreme asymmetry in the 1075 cm-1 P=O2 symmetric stretch band developed to lower energy. The integrated intensity ratio of the 875 cm-1 band to the 1075 cm-1 band envelope remained constant. These observations are consistent with anion-anion association via hydrogen bonds. Deconvolution of the spectral bands showed only 40% and 20% of the phosphates exist as monomers in saturated potassium and ammonium solutions, respectively, and that anion association does not cease at the dimer. The spectra provided no evidence of quasi-crystalline entities in solution. The necessary breaking and reforming of hydrogen bonds during the growth process can explain rapid z-direction growth, growth activation energy, and the rate-limiting surface growth mechanism.
17.	Chakraborty, Reena, et al. (författare) Steady state fluorescence spectroscopy of pyranine as a trace extrinsic probe to study structure in aqueous sugar solutions 1992 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 125:1-2, s. 81-96 Tidskriftsartikel (refereegranskat)abstract The steady state fluorescence behavior of pyranine has been monitored in aqueous solutions of sucrose, glucose, fructose, and lactose. In each case it is possible to use the ratio of peak intensities at 440 and 511 nm (the PIR) as an indicator of the degree of supersaturation of the sugar solutions. We observed both bulk water and water of solvation in all solutions examined, regardless of degree of sapersaturation. In each case the amounts of bulk water and water of solvation per molecule of sugar appear to be nearly equal at saturation. We did not observe any evidence of solvent exclusive clusters in any of the systems we studied
18.	Danielsson, Örjan, 1973-, et al. (författare) Growth rate predictions of chemical vapor deposited silicon carbide epitaxial layers 2002 Ingår i: Journal of Crystal Growth. - : Elsevier. - 0022-0248 .- 1873-5002. ; 243:1, s. 170-184 Tidskriftsartikel (refereegranskat)abstract Complete 3D simulations of a silicon carbide chemical vapor deposition (CVD) reactor, including inductive heating and fluid dynamics as well as gas phase and surface chemistry, have been performed. For the validation of simulated results, growth was conducted in a horizontal hot-wall CVD reactor operating at 1600°C, using SiH4 and C3H8 as precursor gases. Simulations were performed for an experimental hot-wall CVD reactor, but the results are applicable to any reactor configuration since no adjustable parameters were used to fit experimental data. The simulated results obtained are in very good agreement with experimental values. It is shown that including etching and parasitic growth on all reactor walls exposed to the gas greatly improves the accuracy of the simulations. © 2002 Elsevier Science B.V. All rights reserved.
19.	Danielsson, Örjan, et al. (författare) Investigation of the temperature profile in a hot-wall SiC chemical vapour deposition reactor 2002 Ingår i: Journal of Crystal Growth. - : ScienceDirect. - 0022-0248 .- 1873-5002. ; 235:1-4, s. 352-364 Tidskriftsartikel (refereegranskat)abstract The chemical vapor deposition (CVD) technique is widely used to grow epitaxial layers of silicon carbide. To meet the demands for high quality epitaxial layers, which have good morphology and a minimum variation of the doping and thickness, a good knowledge of the CVD process is essential. The present work uses a simulation tool to investigate several parameters influencing the heating of a hot-wall CVD reactor. The simulations are set up as 2D axisymmetric problems and validation is made in a 2D horizontal hot-wall CVD reactor. By applying the knowledge achieved from the simulations, the temperature profile is optimized to give as large area as possible with homogeneous temperature. New susceptor and coil designs are tested. A very good agreement between the simulated and the measured results is obtained. The new design has a temperature variation of less than 0.5% over more than 70% of the total susceptor length at an operating temperature of 1650°C. In addition, the power input needed to reach the operating temperature is decreased by 15% compared to the original design. 3D simulations are performed to show that the changes made in the 2D case give similar results for the real 3D case.
20.	Danielsson, Örjan, et al. (författare) Predicted nitrogen doping concentrations in silicon carbide epitaxial layers grown by hot-wall chemical vapor deposition 2003 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 250:3-4, s. 471-478 Tidskriftsartikel (refereegranskat)abstract A simple quantitative model for the surface adsorption of nitrogen has been developed to simulate the doping incorporation in intentionally doped 4H-SiC samples during epitaxial growth. Different reaction schemes are necessary for the two faces of SiC. The differences are discussed, and implications to the necessary model adjustments are stressed. The simulations are validated by experimental values for a large number of different process parameters with good agreement.
21.	Danielsson, Örjan, et al. (författare) Reducing stress in silicon carbide epitaxial layers 2003 Ingår i: Journal of Crystal Growth. - : Elsevier. - 0022-0248 .- 1873-5002. ; 252:1-3, s. 289-296 Tidskriftsartikel (refereegranskat)abstract A susceptor for the epitaxial growth of silicon carbide, with an up-lifted substrate holder, is investigated and compared to other susceptor designs both experimentally and by the use of computational fluid dynamics simulations. It is shown that the wafer bending due to temperature gradients is diminished in a hot-wall reactor compared to growth in a cold-wall reactor. The substrate backside growth is diminished using the up-lifted substrate holder, limiting the substrate bending due to the backside growth. Thereby the stress built into the epitaxial layers during growth is significantly reduced. Simulations indicate a lower effective C/Si ratio over the wafer, and a lower preferable growth temperature, as compared to the original susceptor design. In addition a slightly higher growth rate is achieved
22.	Danielsson, Örjan, et al. (författare) Using N2 as precursor gas in III-nitride CVD growth 2003 Ingår i: Journal of Crystal Growth. - : Elsevier. - 0022-0248 .- 1873-5002. ; 253:1-4, s. 26-37 Tidskriftsartikel (refereegranskat)abstract Computational fluid dynamics simulations have been performed to explore the possibility of using nitrogen gas as a precursor to III-nitride growth. A chemical model for the gas-phase decomposition of N2 has been used to show that large enough amounts of reactive species can be formed under conditions not far from those used in normal metalorganic chemical vapor deposition. Simulations were performed in 2D for various concentrations of N2, and comparisons with the use of NH3 were made. A modified reactor design needed to achieve high enough concentrations of reactive species is suggested. The possibility to increase the growth rate and material quality in III-nitride growth is discussed.
23.	Dunuwila, Dilum D., et al. (författare) An investigation of the applicability of attenuated total reflection infrared spectroscopy for measurement of solubility and supersaturation of aqueous citric acid solutions 1994 Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 137:3-4, s. 561-568 Tidskriftsartikel (refereegranskat)abstract Currently applied methods for measurement of solubility and supersaturation based on viscometry, refractometry, interferometry and density require the separation of phases prior to measurement. ATR (attenuated total reflection) infrared spectroscopy provides a unique configuration in which the infrared spectrum of a liquid phase can be obtained in a slurry without phase separation. The applicability of the technique was investigated using a micro Circle® open boat cell equipped with a ZnSe (zinc selenide) ATR rod. Experiments conducted with aqueous citric acid proved that ATR infrared spectroscopy can be successfully employed to determine solubility and supersaturation.
24.	Dunuwila, D.D., et al. (författare) ATR FTIR spectroscopy for in situ measurement of supersaturation 1997 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 179:1-2, s. 185-193 Tidskriftsartikel (refereegranskat)abstract The current contribution establishes the technical feasibility of Attenuated Total Reflection (ATR) Fourier transform infrared (FTIR) spectroscopy for the in situ measurement of supersaturation in crystallization processes. The approach was inspired by recent advancements in ATR spectroscopy by way of various light transfer systems for remote sensing and by the increasing availability of ATR configurations well suited for remote, in situ measurements. The feasibility of the technique was investigated using a DIPPER-210® immersion probe manufactured by Axiom Analytical, Inc. Initial experiments conducted using aqueous maleic acid proved that ATR FTIR spectroscopy can be successfully employed to measure supersaturation, solubility and the metastable limit, in situ, with sufficient accuracy and precision.
25.	Ellison, A., et al. (författare) Epitaxial growth of SiC in a chimney CVD reactor 2002 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 236:1-3, s. 225-238 Tidskriftsartikel (refereegranskat)abstract A high growth rate (>10 µm/h) Chemical Vapour Deposition (CVD) process is investigated in a vertical hot-wall, or "chimney", reactor. By the use of increased temperatures (1650-1850°C) and concentrations of reactants, this process is shown to enable growth rates up to 50µm/h and demonstrates a material quality comparable to established CVD techniques until growth rates of 25 µm/h. The gas flow dynamics, the growth rate and the thickness uniformity determining steps are investigated, and the role of homogenous nucleation is analysed. The growth rate is shown to be influenced by two competing processes: the supply of growth species and the etching of the hydrogen carrier gas. The exponential increase of the growth rate with temperature is related to a Si-vapour release from clusters homogeneously nucleated in the inlet of the susceptor and acting as a growth species reservoir. © 2002 Elsevier Science B.V. All rights reserved.
26.	Fernandez, J. R. L., et al. (författare) Electrical resistivity and band-gap shift of Si-doped GaN and metal-nonmetal transition in cubic GaN, InN and AlN systems 2001 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 231:3, s. 420-427 Tidskriftsartikel (refereegranskat)abstract The critical impurity concentration N-c of the metal-nonmetal (MNM) transition for the cubic GaN, InN and AIN systems. is calculated using the following two different criteria: vanishing of the donor binding energy and the crossing point between the energies in the metallic and insulating phases. A dielectric function model with a Lorentz-Lorenz correction is used for the insulating phase. The InN presents an order of magnitude increase in N-c as compared to the other two systems. The electrical resistivity of the Si-donor system GaN is investigated theoretically and experimentally from room temperature down to 10K. It presents a metallic character above a certain high impurity concentration identified as N-c. The samples were grown by plasma assisted molecular beam epitaxy (MBE) on GaAs (0 0 1) substrate. The model calculation is carried out from a recently proposed generalized Drude approach (GDA) presenting a very good estimation for the metallic region. The band-gap shift (BGS) of Si-doped GaN has also been investigated above the MNM transition where this shift is observed. Theoretical and experimental results have a rough agreement in a range of impurity concentration of interest.
27.	Forsberg, U., et al. (författare) Aluminum doping of epitaxial silicon carbide 2003 Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 253:04-jan, s. 340-350 Tidskriftsartikel (refereegranskat)abstract Intentional doping of aluminum in 4H and 6H SiC has been performed using a hot-wall CVD reactor. The dependence of aluminum incorporation on temperature, pressure, C/Si ratio, growth rate, and TMA flow has been investigated. The aluminum incorporation showed to be polarity dependent. The high aluminum incorporation on the Si-face is closely related to the carbon coverage on the SiC surface. Changes in process parameters changes the effective C/Si ratio close to the SiC surface. Increased growth rate and C/Si ratio increases the aluminum incorporation on the Si-face. Diffusion limited incorporation occurs at high growth rate. Reduced pressure increases the effective C/Si ratio, and at low growth rate, the aluminum incorporation increases initially, levels off at a critical pressure, and continues to decrease below the critical pressure. The aluminum incorporation showed to be constant in a temperature range of 50degreesC. The highest atomic concentration of aluminum observed in this study was 3 x 10(17) and 8 x 10(18) cm(-3) in Si and C-face, respectively.
28.	Forsberg, Urban, 1971-, et al. (författare) Aluminum doping of epitaxial Silicon Carbide 2003 Ingår i: Journal of Crystal Growth. - : ScienceDirect. - 0022-0248 .- 1873-5002. ; 253:1-4, s. 340-350 Tidskriftsartikel (refereegranskat)abstract Intentional doping of aluminum in 4H and 6H SiC has been performed using a hot-wall CVD reactor. The dependence of aluminum incorporation on temperature, pressure, C/Si ratio, growth rate, and TMA flow has been investigated. The aluminum incorporation showed to be polarity dependent. The high aluminum incorporation on the Si-face is closely related to the carbon coverage on the SiC surface. Changes in process parameters changes the effective C/Si ratio close to the SiC surface. Increased growth rate and C/Si ratio increases the aluminum incorporation on the Si-face. Diffusion limited incorporation occurs at high growth rate. Reduced pressure increases the effective C/Si ratio, and at low growth rate, the aluminum incorporation increases initially, levels off at a critical pressure, and continues to decrease below the critical pressure. The aluminum incorporation showed to be constant in a temperature range of 50°C. The highest atomic concentration of aluminum observed in this study was 3×1017 and 8×1018 cm−3 in Si and C-face, respectively.
29.	Forsberg, Urban, 1971-, et al. (författare) Nitrogen doping of epitaxial Silicon Carbide 2002 Ingår i: Journal of Crystal Growth. - : ScienceDirect. - 0022-0248 .- 1873-5002. ; 236:1-3, s. 101-112 Tidskriftsartikel (refereegranskat)abstract Intentional doping with nitrogen of 4H- and 6H-SiC has been performed using a hot-wall CVD reactor. The nitrogen doping dependence on the temperature, pressure, C/Si ratio, growth rate and nitrogen flow has been investigated. The nitrogen incorporation for C-face material showed to be C/Si ratio independent, whereas the doping decreased with increasing C/Si ratio for the Si-face material in accordance with the “site-competition” model. The nitrogen incorporation was constant in a temperature “window” of 75°C on Si-face material indicating a mass transport limited incorporation. Increasing the growth rate resulted in a decrease of nitrogen incorporation on Si-face but an increase on C-face material. Finally, a comparison between previously published results on cold-wall CVD-grown material and the present hot-wall-grown material is presented.
30.	Gaarder, A., et al. (författare) Dopant distribution in selectively regrown InP : Fe studied by time-resolved photoluminescence 2001 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 226:4, s. 451-457 Tidskriftsartikel (refereegranskat)abstract We apply time-resolved photoluminescence with 1 mum spatial resolution for the characterization of iron distribution in semi-insulating InP:Fe epitaxial layers regrown by hydride vapor-phase epitaxy around etched mesas. The InP:Fe regrowth was carried out on InP:S mesas etched both along the [110] and [110] crystallographic directions, as well as on InP/InGaAsP in-plane lasers. In all cases, the Fe concentration was found to be close to the target values and showed little variation along the regrown layers.
31.	Godlewski, M., et al. (författare) Quasi-zero-dimensional excitons in quantum well structures of CdTe/CdMnTe 2000 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 214, s. 420-423 Tidskriftsartikel (refereegranskat)abstract In this work we discuss properties of excitons in quantum well structures of CdTe/CdMnTe. We analyse exciton-phonon interaction of strongly localised excitons by studying the temperature dependence of photoluminescence (PL) (width and spectral position of PL lines) and PL dynamics. Evidence of a slow exciton migration/tunnelling among localised sites is presented and its effect on the luminescence spectrum and exciton dynamics is discussed. We show that strong localisation of excitons, observed at low temperatures, results in quasi-zero-dimensional nature of excitons.
32.	Guo, S.J., et al. (författare) Improved single crystal growth in the Bi-Sr-Ca-Cu-O system using a sealed cavity technique 1990 Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 100:1-2, s. 303-308 Tidskriftsartikel (refereegranskat)abstract Bi-Sr-Ca-Cu-O single crystals obtained thus far commonly have a very small thickness in the c-axis because of the weak bonding between two adjacent BiO layers and the high vapour pressure of Bi2O3 at high temperature. To overcome these difficulties a presintered SrCaCu4O6 was used to seal the Bi-Sr-Ca-Cu-O melt from which the single crystals grew during slow cooling. In the SrCaCu4O6 sealed cavity the Bi loss through vaporization was prevented and Sr and Ca were enriched in the superconducting crystals. The resulting single crystals have a dimension of up to 3.0×1.5×0.7 mm3, which is two orders of magnitude thicker than those grown from alkali chloride flux. The composition of the crystals is Bi2.2Sr1.8Ca0.75Cu1.8Ox and they possess a zero resistance at temperature above liquid nitrogen
33.	Hogberg, H., et al. (författare) Strain relaxation of low-temperature deposited epitaxial titanium-carbide films 2000 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 219:3, s. 237-244 Tidskriftsartikel (refereegranskat)abstract The lattice misfit strain and relaxation during growth of 60-950 angstroms epitaxial TiC carbide films deposited by co-evaporation of C60 and Ti on MgO(0 0 1) have been studied by reciprocal space mapping (RSM) and transmission electron microscopy (TEM). All the films exhibited a strained layer growth behavior with respect to the substrate. The strain e, ranged from 2.1% for the 60 angstroms film to 0.8% for the 950 angstroms film. Initial misfit strain relaxation was by slip on {1 1 0}<1 0 1¯> and {1 1 1}<1 0 1¯>. After dislocation rearrangement the films predominantly exhibited well-developed misfit dislocations of edge type with line direction <1 0 0> along the interface plane and Burgers vectors 1/2[1 0 1¯] inclined to the interface with MgO.
34.	Hu, Hanmei, et al. (författare) Solvothermal synthesis of Sb2S3 nanowires on a large scale 2003 Ingår i: Journal of Crystal Growth. - : Elsevier. - 0022-0248 .- 1873-5002. ; 258:1-2, s. 106-112 Tidskriftsartikel (refereegranskat)abstract Sb2S3 nanowires with high aspect ratios have been successfully prepared on a large scale using SbCl3 and Na2S as starting materials in ethylene glycol at 200°C for 10 h. Field emission scanning electron microscopy images and transmission electron microscopy images show that the nanowires have diameters in the range of 20–100 nm and lengths up to 50 μm. Diffuse reflection spectrum indicates that the as-prepared Sb2S3 nanowires have obvious quantum size effects. The effects of reaction parameters on the growth of nanowires were discussed. A possible mechanism on the formation of the Sb2S3 nanowires was proposed.
35.	Ivanov, S.V., et al. (författare) MBE growth and properties of bulk BeCdSe alloys and digital (BeSe : CdSe)/ZnSe quantum wells 2000 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 214, s. 109-114 Tidskriftsartikel (refereegranskat)abstract We report for the first time on MBE growth, structural and optical properties of single layers, quantum well structures and short-period superlattices based on BexCd1-xSe ternary alloys on GaAs. Both the conventional MBE growth mode and the sub-monolayer digital alloying technique (SDA) have been employed for the fabrication of the structures. Compositional boundaries of an instability region 0.03 < x < 0.38, calculated in a regular solution approximation for the completely coherent system, agree well with available experimental data. A suppression of the phase separation in BeCdSe by elastic stress in the layer, accompanied by a strong reduction of the Cd incorporation coefficient has been found. Ultrathin 2.8 ML BeCdSe SDA QWs with x approx. 0.15 demonstrate about an order of magnitude increase in the PL intensity with respect to the pure CdSe one, probably resulting from an enhanced carrier localization efficiency. Eg as a function of the Be content reveals a strong bowing in optical data, which allows one to consider BeCdSe alloys with compositions nearly lattice-matched to GaAs as potential materials for the active region of blue-green lasers.
36.	Jacobson, H., et al. (författare) Structural impact of LPE buffer layer on sublimation grown 4H-SiC epilayers 2003 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 256:3-4, s. 276-282 Tidskriftsartikel (refereegranskat)abstract The objective of this work was to study the effect of a liquid phase epitaxy buffer layer on the development of defects in sublimation grown epitaxial layers of 4H-SiC. The results were analyzed with the aid of optical microscope, scanning electron microscope, high-resolution X-ray diffraction and synchrotron white beam X-ray topography. A pronounced effect of the liquid phase epitaxy buffer layer on formation of dislocations and micropipes is observed in the sublimation epitaxy layers. It has been shown that during sublimation growth of epilayer with a thin liquid phase epitaxy buffer layer (0.1µm) defects may undergo transformation and stacking faults can be formed. Sublimation grown epilayers grown on a thick liquid phase epitaxy buffer layer (1µm) also showed a symmetrical distribution of misfit dislocations along the <112¯0> and [11¯00] directions. © 2003 Elsevier B.V. All rights reserved.
37.	Ji, W, et al. (författare) 3-D computational modeling of SiC epitaxial growth in a hot wall reactor 2000 Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 220:4, s. 560-571 Tidskriftsartikel (refereegranskat)abstract A three-dimensional computational model for chemical vapor deposition (CVD) of silicon carbide (SiC) in a hot wall reactor is developed, where the susceptor is tapered with a rectangular cross-section. The present work focuses on the advection-diffusion-reaction process in the susceptor. The precursors are propane and silane, and the carrier gas is hydrogen with mass fraction higher than 98%. Computed growth rates under different system pressures and precursor concentrations are compared with the experimental data measured on samples grown in the Linkoping CVD reactor. The gas composition distribution and the growth rate profile are shown. Dependence of the growth rate on precursor concentrations is investigated.
38.	Kakanakova-Georgieva, Anelia, 1970-, et al. (författare) Kinetics of residual doping in 4H-SiC epitaxial layers grown in vacuum 2002 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 240:04-mar, s. 501-507 Tidskriftsartikel (refereegranskat)abstract Investigation on residual Al, B, and N co-doping of 4H-SiC epitaxial layers is reported. The layers were produced by sublimation epitaxy in Ta growth cell environment at different growth temperatures and characterized by secondary ion mass spectrometry. The vapor interaction with Ta was considered through calculations of cohesive energies of several Si-, Al-, B-, and N-containing vapor molecules and also of diatomic Ta-X molecules. An analysis of kinetic mechanisms responsible for impurity incorporation is performed. Among residuals, B exhibits a stronger incorporation dependence on temperature and growth at lower temperatures can favor B decrease in the layers. Under the growth conditions in this study (Ta environment and presence of attendant Al and N), B incorporation is assisted by Si2C vapor molecule. Boron tends to occupy carbon sites at higher temperatures, i.e. higher growth rates.
39.	Kugler, Veronika Mozhdeh, et al. (författare) Low temperature growth and characterization of (Na,K)NbOx thin films 2003 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 254:3-4, s. 400-404 Tidskriftsartikel (refereegranskat)abstract Thin (Na,K)NbOx perovskite films (NKN) have been deposited on SiO2/Si(0 0 1) substrates at low temperatures, from 350°C to 550°C, by RF magnetron sputtering. The effects of substrate temperature on microstructure, electrical-, and mechanical properties of the NKN films have been studied. X-ray diffraction analysis revealed that films deposited at temperatures in the range of 450-550°C were crystalline, growing as a single phase, with a preferred orientation of (0 0 1). Films deposited at 350°C, were shown to be amorphous. The growth temperature had a strong influence on the electrical properties of the NKN films and the relative dielectric constants of the obtained films were in between 38 and 78. Variations of the mechanical properties of the NKN films were observed for different substrate temperatures: The elastic moduli and the hardness values ranged from 205±26 to 93±29 GPa, and from 12±2 to around 2 GPa, for films deposited at 550°C and 450°C, respectively.
40.	LeCaptain, D.J., et al. (författare) Applicability of second harmonic generation for in situ measurement of induction time of selected crystallization systems 1999 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 203:4, s. 564-569 Tidskriftsartikel (refereegranskat)abstract The nonlinear optical technique of second harmonic generation (SHG) is introduced as a novel technique for monitoring particle formation in batch crystallizations. SHG is more sensitive and is less prone to interference than turbidometric methods. The studies presented show the applicability of SHG as a method for in situ measuring the induction time of a number of noncentrosymmetric crystal systems.
41.	LI, G, et al. (författare) ZN DELTA-DOPED GAAS GROWN BY METALORGANIC VAPOR-PHASE EPITAXY 1995 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 154, s. 231-239 Tidskriftsartikel (refereegranskat)abstract A number of delta-doping parameters have been changed to study their effects on the hole concentration of Zn delta-doped GaAs grown by metalorganic vapour phase epitaxy using dimethylzinc (DMZn) as a doping precursor. We observed that the hole concentration is dependent on the DMZn partial pressure but independent of the gas now velocity in the reactor. A weak effect of the delta-doping time on the hole concentration infers that the near-equilibrium between the Zn adsorption and desorption can be reached very rapidly. In the regime of the delta-doping temperatures from 600 to 700 degrees C, the Zn desorption predominantly determines the hole concentration, and the Zn desorption activation energy obtained from the Arrhenius-type plot is 2.04 eV. Below 600 degrees C, however, the hole concentration departures from the Arrhenius-type relationship with the reciprocal delta-doping temperature, indicating that some other factors start to influence the Zn delta-doping concentration.
42.	Li, K., et al. (författare) MBE-based SiGe/Si heterojunction multilayer structures 2001 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 227-228, s. 744-748 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract In this paper, SiGe/Si multilayer heterostructures prepared by molecular beam epitaxy (MBE) are described with the aim of manufacturing SiGe heterojunction bipolar transistors (HBTs). Based on the simulations made by Medici, device structures have been designed and grown. The quality of the MBE layered structures has been characterized by reflection high-energy electron diffraction, X-ray diffraction, secondary ion mass spectrometry and spreading resistance. Furthermore, SiGe-HBTs have been fabricated. Promising DC and RF results of processed HBT devices have been obtained. © 2001 Elsevier Science B.V.
43.	Madsen, L.D., et al. (författare) Assessment of MgO(1 0 0) and (1 1 1) substrate quality by X-ray diffraction 2000 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 209:1, s. 91-101 Tidskriftsartikel (refereegranskat)abstract MgO{1 1 1} and {1 0 0} crystals are widely used as substrates for thin film growth, in many different areas of research such as superconductors, and other oxide, metal and nitride films, multilayers and superlattices. Since the quality of the thin film can be strongly dependent on that of the substrate, the optimal film properties will only be fully conceived if the substrate is well characterized in advance. The goal of this work was to create a characterization method which was inexpensive, fast, efficient, and of course nondestructive, for assessing imperfect metal-oxide substrates. X-ray diffraction (XRD) was chosen because of its low cost, simplicity, nondestructiveness, and the fact that we have access to many different parameters using the same instrument. The miscut of the MgO crystals studied herein were characterized with a high resolution of 0.01°. The number of domains, their distribution and their size were characterized by ?-f maps and topography measurements. In this case, atomic force microscopy (AFM) was found to be more appropriate for assessing roughness than X-ray reflectivity measurements.
44.	Menon, C., et al. (författare) Defect density in non-selective and selective Si/SiGe structures 2002 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 237, s. 259-263 Tidskriftsartikel (refereegranskat)abstract The epitaxial quality of Si (non-selective or selective epitaxy)/SiGe (non-selective or selective epitaxy) structures applying Si2H2Cl2 or SiH4 as the Si source has been studied. High-resolution reciprocal lattice mapping and X-ray reflectivity measurements have been used to characterise the epitaxial quality and the interfacial defects, respectively. The surface morphology of the structures was studied by atomic force microscopy. It is shown that the generation of defects in non-selective SiGe layers is strongly dependent oil the thickness of the buffer layer. Moreover, the selective growth of a Si buffer layer requires a growth temperature above 770degreesC in order to obtain a smooth layer surface, which is beneficial for the succeeding growth of the SiGe layer. The surface can also be smoothed by an annealing treatment at 900degreesC for 40 s. This annealing step is crucial to remove the interfacial defects in the case of Si/SiGe structures grown with different Si sources.
45.	Messmer, E. R., et al. (författare) In situ mesa etching and immediate regrowth in a HVPE reactor for buried heterostructure device fabrication 2000 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 210:4, s. 600-612 Tidskriftsartikel (refereegranskat)abstract Mesa etching in a hydride vapour-phase epitaxy (HVPE) reactor has been studied. Etched depth. underetching and shape of the mesas have been analysed as a function of partial pressures of active gases (HCl, PPI, and InCl) stripe orientation and etching temperature. The experimental results show that the depth and undercut can be etched independently. We propose qualitative mechanisms for etching each of the emerging crystallographic planes ((0 0 1), ( 1 1 0) and {1 1 1}). In situ mesa etching with immediate regrowth was applied to the fabrication of buried heterostructure Fabry-Perot lasers. No surface contamination due to exposure to ambient and low process time are advantages of this technique.
46.	Ni, Wei-Xin, et al. (författare) X-ray reciprocal space mapping studies of strain relaxation in thin SiGe layers (=100 nm) using a low temperature growth step 2001 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 227-228, s. 756-760 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract Relaxation of thin SiGe layers (~90 nm) grown by molecular beam epitaxy using a low temperature growth step (120-200°C) has been investigated using two-dimensional reciprocal space mapping of X-ray diffraction. The samples studied have been divided in two groups, depending on the substrate cooling process during the growth of the low temperature layer. It has been found that a higher degree of relaxation was easily achieved for the sample group without growth interruption. A process window for full relaxation of the Si0.74Ge0.26 layer has been observed in the range of 140-150°C. © 2001 Elsevier Science B.V.
47.	NORDELL, N, et al. (författare) GROWTH AND PERFORMANCE OF ALGAAS/GAAS HETEROSTRUCTURE BIPOLAR-TRANSISTORS 1991 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 107:1-4, s. 909-914 Tidskriftsartikel (refereegranskat)
48.	NORDELL, N, et al. (författare) INFLUENCE OF MOVPE GROWTH-CONDITIONS AND CCL4 ADDITION ON INP CRYSTAL SHAPES 1992 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 125:3-4, s. 597-611 Tidskriftsartikel (refereegranskat)
49.	NORDELL, N, et al. (författare) MOVPE GROWTH OF INP AROUND REACTIVE ION ETCHED MESAS 1991 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 114:1-2, s. 92-98 Tidskriftsartikel (refereegranskat)
50.	Palmquist, J.-P., et al. (författare) Epitaxial growth of tungsten carbide films using C60 as carbon precursor 2003 Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 259:1-2, s. 12-17 Tidskriftsartikel (refereegranskat)abstract In this paper we present the first results from processing and characterisation of epitaxial tungsten carbide films. The films were deposited in ultra-high vacuum by DC magnetron sputtering of tungsten with co-evaporated C60 as carbon source. It was found that the growth rate was crucial for the crystalline film quality. Epitaxial growth of ß-WC1-x could be achieved at 400°C using a very low deposition rate of 6Å/min. Single-crystal films were thus formed on both MgO(100) and MgO(111). High-resolution transmission electron microscopy shows that the films grow with a very good match relative the substrate. Deposition rates of 10Å/min and higher resulted in renucleation and nanocrystalline growth with grain sizes of 15-80Å depending on substrate temperature. We have also found that a small addition of titanium stabilises the epitaxial growth of the cubic tungsten carbide films at higher growth rates. A titanium contribution of ~2% give epitaxial growth at deposition rates of 40Å/min. X-ray diffraction study of the epitaxial films using reciprocal space mapping shows a cross-like broadening that is possibly related to ordering. © 2003 Elsevier B.V. All rights reserved.

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