Deep Level Transient Spectrum of As-implanted GaN film

• Main Authors: Wen-chi, Lee, 李文祺
• Other Authors: Wei-Kuo, Chen
• Format: Others
• Language: en_US
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/24563714196206313684

碩士 === 國立交通大學 === 電子物理系 === 89 === Deep Level Transient Spectrum of As-implanted GaN film Student：Wen-Chi Lee Advisor：Prof. Wei-Kuo Chen Institute of Electrophysics National Chiao Tung University Abstract Deep Level Transient Spectrum (DLTS) and Photoluminescence(PL)、Photoluminescence Excitation(PLE) have been utilized to investigate defects in As-implanted GaN film. We attempted to understand the mechanism of Arsenic impurity in GaN. We found from PL spectrum that the I2 and YL emission reduced a great amount while a new As-related broad band emerged. According to the PLE spectrum, the origin of YL emission in our sample was gallium vacancy, which is a deep acceptor in the band gap. Absorption spectrum then revealed that a greater absorption rate has taken place around 470nm~485nm. Therefore, there might be a wide energy band exists around 470nm~485nm and caused more absorption. We only observed an energy level A1’ at 0.859eV below conduction band in our undoped sample. On the other hand, we found three new energy levels E1’, E2’, EAs (0.16eV, 0.6eV, 0.766eV below the conduction band individually) and diminished A1’ in our As-implanted sample. Particularly, the intensity of EAs increases as the dosage of As-implantation increases, i.e. EAs is a As-related defect. We then propose the possibility of As atom occupying gallium vacancy. This suggestion can reasonably explain our observations. First, the YL emission declined for the gallium vacancies being occupied by As atoms. And the defect AsGa would be a deep double donor in band gap, this concept consists with the position of EAs measured in DLTS and the position of greater absorption in absorption rate spectrum. We therefore conjecture that As-implantation caused the As atom to replace gallium vacancy and decrease of YL emission and introduction of As-related emission.