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Title: Elimination of surface band bending on N-polar InN with thin GaN capping

0.5–1 μm thick InN (0001) films grown by molecular-beam epitaxy with N- or In-polarity are investigated for the presence of native oxide, surface energy band bending, and effects introduced by 2 to 4 monolayers of GaN capping. Ex situ angle-resolved x-ray photo-electron spectroscopy is used to construct near-surface (GaN)/InN energy profiles, which is combined with deconvolution of In3d signal to trace the presence of InN native oxide for different types of polarity and capping. Downwards surface energy band bending was observed on bare samples with native oxide, regardless of the polarity. It was found that the In-polar InN surface is most readily oxidized, however, with only slightly less band bending if compared with the N-polar sample. On the other hand, InN surface oxidation was effectively mitigated by GaN capping. Still, as confirmed by ultra-violet photo-electron spectroscopy and by energy band diagram calculations, thin GaN cap layer may provide negative piezoelectric polarization charge at the GaN/InN hetero-interface of the N-polar sample, in addition to the passivation effect. These effects raised the band diagram up by about 0.65 eV, reaching a flat-band profile.
Authors:
; ; ; ;  [1] ;  [2] ;  [3] ; ;  [4] ;  [5]
  1. Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravska cesta 9, 841 04 Bratislava (Slovakia)
  2. Microelectronics Research Group (MRG), IESL, FORTH, P.O. Box 1385, 71110 Heraklion, Crete (Greece)
  3. Polymer Institute, Slovak Academy of Sciences, Dúbravska cesta 9, 845 41 Bratislava (Slovakia)
  4. Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, Mlynská dolina, 842 48 Bratislava (Slovakia)
  5. Microelectronics Research Group (MRG), IESL, FORTH, P.O. Box 1385, 71110 Heraklion, Greece and Department of Physics, University of Crete, 71203 Heraklion (Greece)
Publication Date:
OSTI Identifier:
22486039
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 19; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ELECTRON SPECTROSCOPY; ELECTRONIC STRUCTURE; FILMS; GALLIUM NITRIDES; INDIUM NITRIDES; INTERFACES; LAYERS; MOLECULAR BEAM EPITAXY; OXIDATION; OXIDES; PIEZOELECTRICITY; POLARIZATION; SIGNALS; SURFACE ENERGY; SURFACES; X RADIATION