Fabrication of Integrated Ⅲ-Nitride Compound Semiconductor Based Gas Sensors

• Main Authors: Chung-Fu Chang, 張仲甫
• Other Authors: Wen-Chau Liu
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/19031959657866434105

碩士 === 國立成功大學 === 微電子工程研究所碩博士班 === 97 === 　　Over the past decades, different types of gas sensors were developed. With the quick development of the fabrication technologies, semiconductor based gas sensors with small size and high sensitivity have become the mainstream of the research process. 　　The studied integrated sensors consisted of different catalytic metals such as Pd, Pt and ZnO. The studied devices are capable of monitoring different gases such as hydrogen, ammonia, and nitrogen dioxide. The AlGaN/GaN layer was used because of its advantages including large band gap (4.3eV), wide operation temperature region, good chemical stability, and high density of two-dimensional electron gas. First, the hydrogen-detection characteristics of a Pd/AlGaN/GaN Schottky diode-type sensor were studied and demonstrated at different temperatures. This device exhibited good sensing performance including high relative sensitivity ratio, large current variation, widespread reverse voltage regime, and fast response time. 　　Second, the ammonia-detection characteristics of a Pt/AlGaN/GaN Schottky diode-type sensor were studied and demonstrated. Pt catalytic metal dissociates not only hydrogen molecules but also ammonia molecules. At high temperatures, the device exhibited fast transient response time. Finally, the nitrogen dioxide-detection characteristics of a ZnO/AlGaN/GaN resistor-type sensor were studied and demonstrated. Based on the sensing mechanism of metal-oxide material, the oxidizing property of nitrogen dioxide leads to the decrease of ZnO conductance. 　　In this research, the resistor-type sensor was fabricated with lower resistance to increase the sensitivity. Besides, sensors with large current variation exhibit larger margins to noise interference. Consequently, the integrated sensors show the promise for smart gas sensors and micro-electro-mechanical system (MEMS) application.