X‐ray absorption spectroscopy in the analysis of GaN thin films

Abstract

Stoichiometric amorphous GaN thin films have been grown by an ion-assisted deposition method and examined by x-ray photoelectron spectroscopy and x-ray absorption near-edge spectroscopy (XANES). The crucial question is the nature of the local structure around the N and Ga in the x-ray amorphous films. The N K edge XANES has been used to determine coordination around the N centre and reveals substantial differences to crystalline GaN. Although the transitions observed mirror those of the crystalline material and are consistent with density of states calculations, the low-energy peak at ∼402 eV is dominant in all films less than ∼150 nm in thickness. This peak, initially attributed to an sp 2 environment, is associated with the presence of molecular nitrogen. For thicker films, a duplex-type structure is observed with a surface layer much closer to the structure of the crystalline material.

Facile synthesis and photoluminescence spectroscopy of 3D-triangular GaN nano prism islands

“…The component of BE at 18.4 eV signifies the presence of metallic Gallium adlayer (Ga-Ga) in the sample. 1,18 Further, a chemical shift (1.4-1.5 eV) in the BE position of the dominating peak to the BE of the metallic Gallium peak has been observed in deconvoluted Ga (3d 5/2 ) CL spectra. The shift in the BE position is caused by a subtle change of the inner electron binding energy due to different chemical environments which arise from the difference between atomic valences.…”

“…Thus the presence of a peak at 20.2 eV confirms the bonding between Ga and N atoms and describes the formation of the GaN bond. 1,18 The occurrence of metallic Ga in Ga (3d 5/2 ) CL spectra indicates the presence of Ga atoms which did not interact with the N species. Furthermore, there is a strong tendency for GaN surfaces to be stabilized by Ga atoms in the surface layers due to the small lattice constant and high anion-anion bond strength for GaN compared to those of conventional III-V semiconductors.…”

The use of the X-ray absorption near edge spectrum in materials characterisation

“…Perhaps the most detailed study has been the examination of the N K edge spectrum in amorphous ion assisted deposition (IAD) deposited GaN thin films [9]. These studies reveal exceptional chemical detail with the surprising revelation of the complete vibrational spectrum of molecular nitrogen (Fig.…”

Fabrication and improvement of nanopillar InGaN / GaN light-emitting diodes using nanosphere lithography

“…The strong peaks near 400 eV are from Ga LMM Auger transitions. 30 (b) F 1s spectra, (c) Cl 2p and Cl 2s spectra and (d) In 3d spectra are shown for reference, etched and RTA-HCl treated samples. (e) O 1s spectra and peak deconvolution into three components for different samples.…”