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

Abstract

AbstractStoichiometric 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 sp2 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. Copyright © 2003 John Wiley & Sons, Ltd.