Local crystal structure in the vicinity of Cr in doped AlN thin films studied by X-ray absorption spectroscopy

• Published in: Physical chemistry chemical physics : PCCP Vol. 2; no. 18; pp. 1384 - 1391
• Main Authors: Panda, Padmalochan, Ramaseshan, R, Sahoo, Madhusmita, Krishna, Nanda Gopala, Yadav, A. K, Jha, S. N, Bhattacharyya, D
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 2018
• Subjects: Absorption spectroscopy; Aluminum nitride; Annealing; Atomic properties; Chemical analysis; Chromium nitride; Clustering; Crystal structure; Crystallization; Dopants; Fine structure; Manganese compounds; Spectroscopic analysis; Spectrum analysis; Synthesis; Thin films; Wurtzite; X ray photoelectron spectroscopy
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c8cp01686k

This article reports the detailed X-ray absorption spectroscopy (XAS) study of Al 1− x Cr x N ( x = 4, 6, 11%) thin films synthesized by the reactive magnetron co-sputtering technique. All these films were crystallized with a hexagonal wurtzite structure with preferential orientation along the a -axis without the formation of any secondary phases. Surface chemical analysis to evaluate the Cr concentration was carried out using X-ray photoelectron spectroscopy. The study confirmed the presence of AlN and Cr in bonding with N. The local crystal structure around the Cr dopant in the as-synthesized and annealed thin films has been analyzed by both the X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) techniques. From XAS, it was found that Cr replaced the Al atom in the AlN lattice and led to a localized CrN species with distorted tetrahedral AlN in the absence of Cr clustering. The bond lengths of (Cr-N) ax , (Cr-N) bs and Cr-Al, extracted from the EXAFS fitting, were found to decrease with the Cr concentration for both the as-synthesized and annealed thin films due to the enhancement of p-d hybridization between the dopant and the host atoms. However, in the annealed 11% Cr film, the bond lengths are larger than the other and tend to match the Cr-N geometry in CrN. This article reports the detailed X-ray absorption spectroscopy (XAS) study of Al 1− x Cr x N ( x = 4, 6, 11%) thin films synthesized by the reactive magnetron co-sputtering technique.