Open AccessLocal structures of nanocrystalline GaN studied by XAFS
Author(s) -
Li Zhongrui,
Wei Shiqiang,
Wang Ying,
Zhang Xinyi,
Lu Kunquan,
Chen Xiaolong
Publication year - 2001
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049501000103
Subject(s) - nanocrystalline material , x ray absorption fine structure , bond length , materials science , coordination number , crystallography , k nearest neighbors algorithm , coordination sphere , atom (system on chip) , extended x ray absorption fine structure , crystal structure , absorption spectroscopy , chemistry , nanotechnology , spectroscopy , ion , optics , physics , organic chemistry , quantum mechanics , artificial intelligence , computer science , embedded system
X‐ray absorption fine structure (XAFS) was used to investigate the local structures around Ga atoms in the hexagonal nanocrystalline and crystalline GaN under 78 and 300 K. For the first nearest neighbor coordination shell of Ga‐N, the average bond length R (0.194 nm), coordination number N (4.0), thermal disorder σ T (0.0052 nm) and static disorder σ S (0.0007 nm) are nearly independent of the measured temperature and crystalline state. This indicates that the Ga‐N covalent bond is much stronger, and the 4 nitrogen atoms in first nearest neighbor around Ga atoms keep the tetrahedral structure (Td). For the second nearest neighbor coordination shell of Ga‐Ga, their bond lengths are about 0.318 nm. However, the σ S (0.0057 nm) of nanocrystalline GaN is 0.0047 nm larger than that of crystalline GaN (0.001nm), and the σ T of nanocrystalline is 0.0053 nm and 0.0085 nm at the temperature of 78 and 300 K, respectively. The result indicates that the difference of local structure around Ga atoms between nanocrystalline and crystalline GaN occurs mainly at the Ga‐Ga second nearest‐neighbor coordination shell. The reason is explained as the local lattice distortion and unsaturated surface atoms existing in nanocrystalline GaN.