Short-range structure of dilute nitride GaAsSbN studied by X-ray absorption spectroscopy
Date Issued
2014
Date
2014
Author(s)
Wang, Bo-Wei
Abstract
This study is about the changes of the short-range configuration of N atoms in dilute nitride GaAsSbN after thermal annealing. We use valence force field model to construct 1000 atoms supercells with different N-centered short-range structure. Then we used FEFF9 program to calculate their XANES(X-ray absorption near edge structure) spectra. The XANES of N K-edge experiment result is compared with the simulations from FEFF9 to realize the short-range structure of N atoms, and the Sb K-edge EXAFS(extended X-ray absorption fine structure) fitting results of average GaSb bond length are compared to the VFF calculation to confirm the results.
After comparing the results of XANES and EXAFS, we find there exist NN1 pairs along [0 0 1] direction with four Sb atoms clustering in their commom second shell, called NN1+Sb4 model. After thermal annealing at 800℃, some part of the NN1 pairs dissociate into isolated N with two Sb atoms clustering in the second shell. After 850℃ annealing, however, the short-range structure of N atoms is the isolated N+Sb2 model.
Subjects
短距離結構
XANES
EXAFS
VFF
FEFF9
Type
thesis
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