Characterization of molecular nitrogen in III-V compound semiconductors by near-edge x-ray absorption fine structure and photoemission spectroscopies

Formation of molecular nitrogen under low-energy nitrogen bombardment of III-V compound semiconductor surfaces has been studied by photoemissionspectroscopy around N 1s core-level and near-edge x-ray absorption fine structure(NEXAFS) around NK edge. Interstitial molecular nitrogen N₂ has been formed in all of the samples under consideration. The presence of N₂ produces a sharp resonance in low-resolution NEXAFSspectra, showing the characteristic vibrational fine structure in high-resolution measurements, and at the same time, a new peak, shifted toward higher binding energies for several eV, in all N 1sphotoemissionspectra.This work was supported by the Australian Synchrotron Research Program, which is funded by the Commonwealth of Australia under the Major National Research Facilities Program, and the Research Grant from the Ministry for Science, Education and Sport of the Republic of Croatia

NEXAFS and XPS study of GaN formation on ion-bombarded GaAs surfaces

interaction of low-energy nitrogen ions (0.3-2 keV N(2)(+)) with GaAs (100) surfaces has been studied by Xray photoemission spectroscopy (XPS) around N 1s and Ga 3d core-levels and near-edge X-ray absorption fine structure (NEXAFS) around the N K-edge, using synchrotron radiation. At the lowest bombardment energy, nitrogen forms bonds with both Ga and As, while Ga-N bonds form preferentially at higher energies. Thermal annealing at temperatures above 350 degrees C promotes formation of GaN on the surface, but it is insufficient to remove disorder introduced by ion implantation. We have identified nitrogen interstitials and anti-sites in NEXAFS spectra, while interstitial molecular nitrogen provides a clear signature in both XPS and NEXAFS. The close similarity between NEWS spectra from thin GaN films and ion-bombarded GaAs samples supports our proposition about formation of thin GaN films on ion-bombarded GaAs. (C) 2009 Published by Elsevier Ltd.

Characterisation of nitrogen-related defects in compound semiconductors by near-edge x-ray absorption fine structure

We have studied the formation of nitrogen-related defects created in compound semiconductors by low-energy ion bombardment (0.3-5 keV N 2+ or Ar+) using near-edge x-ray absorption fine structure (NEXAFS) around the N K-edge. Nitrogen interstitials and antisites have been identified in NEXAFS spectra of InN and GaN in full agreement with theoretical calculations. Several defect levels within the band gap and the conduction band of GaN and InN were clearly resolved in NEXAFS spectra. We attribute these levels to interstitial and antisite nitrogen in good agreement with theoretical calculations. Interstitial molecular nitrogen, N2, has been observed in all samples under consideration. The presence of N2 produces a sharp resonance in low-resolution NEXAFS spectra, showing the characteristic vibrational fine structure in high-resolution measurements

Characterisation of molecular nitrogen in ion-bombarded compound semiconductors by synchrotron-based absorption and emission spectroscopies

We have studied formation of molecular nitrogen under low-energy nitrogen bombardment in a range of compound semiconductors by synchrotron-based X-ray photoelectron spectroscopy (XPS) around N 1s core-level and near-edge X-ray absorption fine structure (NEXAFS) around N K-edge. We have found interstitial molecular nitrogen, N(2), in all samples under consideration. The presence of N(2) produces a sharp resonance in low-resolution NEXAFS spectra at around 400.8 eV, showing the characteristic vibrational fine structure in high-resolution measurements. At the same time, a new peak, shifted towards higher binding energies, emerges in all N 1s photoemission spectra. We have found a shift of 7.6 eV for In-based compounds and 6.7 eV for Ga-based compounds. Our results demonstrate that NEXAFS and core-level XPS are complementary techniques that form a powerful combination for studying molecular nitrogen in compound semiconductors, such as GaSb, InSb, GaAs, InN, GaN or ZnO. (C) 2009 Elsevier Ltd. All rights reserved.

Characterisation of molecular nitrogen in ion-bombarded compound semiconductors by synchrotron-based absorption and emission spectroscopies

We have studied formation of molecular nitrogen under low-energy nitrogen bombardment in a range of compound semiconductors by synchrotron-based X-ray photoelectron spectroscopy (XPS) around N 1s core-level and near-edge X-ray absorption fine structure (NEXAFS) around N K-edge. We have found interstitial molecular nitrogen, N2, in all samples under consideration. The presence of N2 produces a sharp resonance in low-resolution NEXAFS spectra at around 400.8 eV, showing the characteristic vibrational fine structure in high-resolution measurements. At the same time, a new peak, shifted towards higher binding energies, emerges in all N 1s photoemission spectra. We have found a shift of 7.6 eV for In-based compounds and 6.7 eV for Ga-based compounds. Our results demonstrate that NEXAFS and core-level XPS are complementary techniques that form a powerful combination for studying molecular nitrogen in compound semiconductors, such as GaSb, InSb, GaAs, InN, GaN or ZnO