Fabrication of highly oriented c-axis AlN films and their application for UV photodetector

• Main Authors: Chu-Fung Chang, 張褚峰
• Other Authors: Chii-Ruey Lin
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/z2c4nv

碩士 === 國立臺北科技大學 === 機電整合研究所 === 98 === Future missions for space astronomy, defense, science and technology required UV photodetector that possess high sensitivity, high precision, low power loss, and high thermal stability. Recently, aluminum nitride has attracted a worldwide attention for potential applications in UV photodetectors, as it possesses good photoconductive properties, including of wide bandgap (~ 6.2 eV), high thermal conductivity as well as high chemical stability. In this study, to develop the applications metal - semiconductor – metal photodetectors, AlN thin films were deposited onto Si (100) and Sapphire (001) substrate by using unbalanced magnetron sputtering system. Effects of various parameters on properties of coated AlN were investigated to obtain the c-axis AlN films. The obtained AlN thin films were employed to fabricate the Inter Digital Transducer (IDT) by using lithography and lift-off methods. To achieve an Ohmic contact as a conduction current interface for UV detector, the films finally were annealed at 500 oC in argon atmosphere (20 sccm of flow rate), with working pressure of 2x10-2 torr for 10 min. The produced films were characterized by X-ray diffractometry, scanning electron microscopy (SEM), atomic force microscopy (AFM). From X-ray diffraction, nitrogen concentration and RF power have the most significant impact to the deposition of high C-axis AlN films. High C-axis AlN thin films were successfully deposited onto Si (100) substrate with 0.2007o of FWHM and 458.8 nm of thickness, as the RF power was 175 w, 50% of nitrogen concentration, 4 mTorr of working pressure and 3 hours process. The AFM results showed that the roughness were < 5 nm (Rms). The AlN films finally were employed to fabricate UV photodetector. From photoconductivity measurement, as the applied bias voltage was ±10V, the self-detector for UV light irradiation (250-400 nm) has a current gain increases about 3 orders.