Investigation and Fabrication of AlGaN/GaN Heterojunction Metal-Semiconductor-Metal (MSM) Photodetectors

• Main Authors: Ke-Wei Lee, 李格瑋
• Other Authors: Ching-Ting Lee
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/51570307084247432410

碩士 === 國立成功大學 === 微電子工程研究所碩博士班 === 93 === 　　In this dissertation, the structure of GaN–based Schottky diodes and MSM photodetectors were epitaxied on Al2O3 (sapphire) substrates by metalorganic chemical vapor deposition system (MOCVD). Due to the Schottky contact characteristics of the diodes were directly related to performances of the MSM photodetectors, the Schottky diodes were fabricated formerly. We needed to take account of some Schottky parameters including the Schottky barrier height ΦB and the ideality factor n to ensure that devices have better Schottky contact. We also fabricated the AlGaN/GaN MSM photodetectors and measured the performances of MSM photodetectors. 　　First, the high mobility and sheet concentration in room temperature were obtained by Hall measurement. This is well known that the existence of AlGaN/GaN heterojunction with spontaneous and piezoelectric polarization resulting in high sheet carrier densities and high room temperature mobility. Such phenomenon was so-called two-dimensional electron gas (2DEG) and could be proved by capacitance-voltage measurement. 　　From the unexpected measuremental results of the MSM photodetectors, the interface state was the most important part we could consider. In order to prove the existence of interface state density, a capacitance-voltage (C-V) method with illumination was referred to demonstrate.