Effect of High-Temperature Annealing on Yellow and Blue Luminescence of Undoped GaN
CHAI Xu-Zhao, ZHOU Dong, LIU Bin, XIE Zi-Li, HAN Ping**, XIU Xiang-Qian, CHEN Peng, LU Hai, ZHANG Rong, ZHENG You-Dou
School of Electronic Science and Engineering, National Laboratory of Solid State Microstructure, and Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, Nanjing University, Nanjing 210093
Abstract：The effect of high-temperature annealing on the yellow and blue luminescence of the undoped GaN is investigated by photoluminescence (PL) and x-ray photoelectron spectroscopy (XPS). It is found that the band-edge emission in the GaN apparently increases, and the yellow luminescence (YL) and blue luminescence (BL) bands dramatically decrease after annealing at 700°C. At the annealing temperature higher than 900°C, the YL and BL intensities show an enhancement for the nitrogen annealed GaN. This fact should be attributed to the increment of the Ga and N vacancies in the GaN decomposition. However, the integrated PL intensity of the oxygen annealed GaN decreases at the temperature ranging from 900°C to 1000°C. This results from the capture of many photo-generated holes by high-density surface states. XPS characterization confirms that the high-density surface states mainly originate from the incorporation of oxygen atoms into GaN at the high annealing temperature, and even induces the 0.34 eV increment of the upward band bending for the oxygen annealed GaN at 1000°C.
2015, Vol. 32 
