| 1. |
- Adell, Johan, 1980, et al.
(författare)
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Electron spectroscopic studies of nanowires formed by (GaMn)As growth on GaAs(111)B
- 2011
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Ingår i: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 151:11, s. 850-854
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Tidskriftsartikel (refereegranskat)abstract
- Valence band photoemission with photon energies around the Mn2p excitation threshold has been used to study the development of nanowires catalyzed by MnAs particles. A gradual change in the spectra with increasing nanowire length is observed, such that the resonant photoemission eventually dominates over the Auger decay channel. The change is ascribed to dilution of Mn, showing that Mn is transferred from the MnAs particles into the nanowires. (C) 2011 Elsevier Ltd. All rights reserved.
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| 2. |
- Adell, Johan, et al.
(författare)
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Formation of epitaxial MnBi layers on (Ga,Mn)As
- 2009
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121 .- 2469-9950 .- 2469-9969. ; 80:7
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Tidskriftsartikel (refereegranskat)abstract
- The initial growth of MnBi on MnAs-terminated (GaMn)As is studied by means of synchrotron-based photoelectron spectroscopy. From analysis of surface core-level shifts we conclude that a continued epitaxial MnBi layer is formed, in which the MnAs/MnBi interface occurs between As and Bi atomic planes. The well-defined 1×2 surface reconstruction of the MnAs surface is preserved for up to 2 ML of MnBi before clear surface degradation occurs. The MnBi layer appears to be free from intermixed As.
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| 3. |
- Adell, Johan, 1980, et al.
(författare)
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Thermal diffusion of Mn through GaAs overlayers on (Ga, Mn)As
- 2011
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 23:8
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Tidskriftsartikel (refereegranskat)abstract
- Thermally stimulated diffusion of Mn through thin layers of GaAs has been studied by x-ray photoemission. (Ga, Mn)As samples with 5 at% Mn were capped with 4, 6 and 8 monolayer (ML) GaAs, and Mn diffusing through the GaAs was trapped on the surface by means of amorphous As. It was found that the out-diffusion is completely suppressed for an 8 ML thick GaAs film. The short diffusion length is attributed to an electrostatic barrier formed at the (Ga, Mn)As/GaAs interface.
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| 4. |
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| 5. |
- Andreasson, Måns, 1975, et al.
(författare)
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Organic molecular beam deposition system and initial studies of organic layer growth
- 2006
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Ingår i: Physica Scripta. - 1402-4896 .- 0031-8949. ; T126, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- This work describes an organic molecular beam deposition system with substrate entry/exitchamber, buffer chamber and with the possibility to transfer substrate from a III–V molecularbeam deposition system. Flux calibrations of organic molecules and the initial growth oforganic layers are described. For this purpose, the molecules 3,4,9,10 perylene tetra carboxylicdianhydride and copper phtalocyanine were used. Layers were grown on oxidized andhydrogen passivated Si(100), Indium tin oxide and glass respectively. The growth wasinvestigated with atomic force microscopy, reflection high energy electron diffraction andultraviolet photoemission spectroscopy. An investigation with x-ray photoelectron and Ramanspectroscopy on the effect of atmospheric exposure is also included, showing little effect ofsurface pollution when the samples were handled carefully. The initial formation (monolayers)of copper phtalocyanine thin films was studied by ultraviolet photoemission spectroscopy.
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| 6. |
- Guziewicz, E., et al.
(författare)
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Mn on the surface of ZnO(0001) - a resonant photoemisson study
- 2005
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Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T115, s. 541-544
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of Mn/ZnO system has been invesigated by synchrotron radiation photoemission. Manganese vacuum deposition was done at room temperature onto a ZnO(0001) single crystal for coverage Mn-Theta <= 4 ML. Photoemission spectra taken near the Mn3p-Mn3d absorption edge after each deposition step show resonant enhancement of Mn3d states within 10 eV of the Fermi edge. The experimentally deduced partial Mn3d density of states for Theta >= 1.2 ML shows at least three features: a major Mn3d structure at 3.8-4.5 eV below the Fermi edge, a valence structure at lower binding energy (1-3 eV) and a broad satelite in the 5.5-9 eV range. The branching ratio of satellite/main structure increases with depostion from 0.33 for 0.4 ML to 0.65 for 4 ML. After annealing up to 500 degrees C the satellite/main ratio decreases to 0.43 indicating a high degree of hybridization between the Mn3d states and valence band of ZnO. After annealing no manganese cap layer was found at the crystal surfaces as was confirmed by the lack of metallic Fermi edge in photoemission spectra and by scanning Auger spectroscopy experiment. The photoemission Mn3p core level spectra taken after annealing consist of two components separated by about 4 eV, which shows that at least two manganese states are observed in the Mn-ZnO interface region.
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| 7. |
- Kanski, Janusz, 1946, et al.
(författare)
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Electronic structure of (Ga,Mn)As revisited
- 2017
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Ingår i: New Journal of Physics. - : Institute of Physics (IOP). - 1367-2630. ; 19:2, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- The detailed nature of electronic states mediating ferromagnetic coupling in dilute magnetic semiconductors, specifically (Ga,Mn)As, has been an issue of long debate. Two confronting models have been discussed emphasizing host band vs. impurity band carriers. Using angle resolved photoemission we show that the electronic structure of the (Ga,Mn)As system is significantly modified from that of GaAs throughout the valence band. Close to the Fermi energy, the presence of Mn induces a strong mixing of the bulk bands of GaAs, which results in the appearance of a highly dispersive band in the gap region of GaAs.For Mn concentrations above 1% the band reaches the Fermi level, and can thus host the delocalized holes needed for ferromagnetic coupling. Overall, our data provide a firm evidence of delocalized carriers belonging to the modified host valence band.
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| 8. |
- Kanski, Janusz, 1946, et al.
(författare)
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Mn-induced modifications of Ga 3d photoemission from (Ga, Mn)As: evidence for long range effects
- 2012
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Ingår i: Journal of Physics: Condensed Matter. - : IOP Publishing. - 1361-648X .- 0953-8984. ; 24:43, s. 1-435802
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Tidskriftsartikel (refereegranskat)abstract
- Using synchrotron based photoemission, we have investigated the Mn-induced changes in Ga 3d core level spectra from as-grown Ga(1-x)Mn(x)As. Although Mn is located in Ga substitutional sites, and therefore does not have any Ga nearest neighbors, the impact of Mn on the Ga core level spectra is pronounced even at Mn concentrations in the region of 0.5%. The analysis shows that each Mn atom affects a volume corresponding to a sphere with around 1.4 nm diameter.
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| 9. |
- Laukkanen, P., et al.
(författare)
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Ultrathin (1x2)-Sn layer on GaAs(100) and InAs(100) substrates : A catalyst for removal of amorphous surface oxides
- 2011
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 98:23, s. 231908-1-231908-3
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Tidskriftsartikel (refereegranskat)abstract
- Amorphous surface oxides of III-V semiconductors are harmful in many contexts of device development. Using low-energy electron diffraction and photoelectron spectroscopy, we demonstrate that surface oxides formed at Sn-capped GaAs(100) and InAs(100) surfaces in air are effectively removed by heating. This Sn-mediated oxide desorption procedure results in the initial well-defined Sn-stabilized (1x2) surface even for samples exposed to air for a prolonged time. Based on ab initio calculations we propose that the phenomenon is due to indirect and direct effects of Sn. The Sn-induced surface composition weakens oxygen adsorption.
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| 10. |
- Nicolai, L., et al.
(författare)
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Bi ultra-thin crystalline films on InAs(111)A and B substrates: a combined core-level and valence-band angle-resolved and dichroic photoemission study
- 2019
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 21:12
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Tidskriftsartikel (refereegranskat)abstract
- The growth of Bi on both the In-terminated (A) face and the As-terminated (B) face of InAs(111) has been investigated by low-energy electron diffraction, scanning tunnelling microscopy, and photoelectron spectroscopy using synchrotron radiation. The changes upon Bi deposition of the In 4d and Bi 5d(5/2) photoelectron signals allow to get a comprehensive picture of the Bi/InAs(111) interface. From the early stage the Bi growth on the A face is epitaxial, contrary to that on the B face that proceeds via the formation of islands. Angle-resolved photoelectron spectra show that the electronic structure of a Bi deposit of approximate to 10 bi-layers on the A face is identical to that of bulk Bi, while more than approximate to 30 bi-layers are needed for the B face. Both bulk and surface electronic states observed are well accounted for by fully relativistic ab initio calculations performed using the one-step model of photoemission. These calculations are used to analyse the dichroic photoemission data recorded in the vicinity of the Fermi level around the (Gamma) over bar point of the Brillouin zone.
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