Simulation and Study of the Hysteresis, Drift and Temperature Effect of the pH-ISFET Based on Hydrogenated Amorphous Silicon and Amorphous Tungsten Oxide

• Main Authors: Jin-Sung Lin, 林金松
• Other Authors: Jung-Chuan Chou
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/75316965385850782826

碩士 === 國立雲林科技大學 === 電子工程與資訊工程技術研究所 === 87 === The ion-sensitive field-effect transistor (ISFET) was developed in 1970s. It has potential advantages over conventional ion selective electrodes in their small size, rapid response, high input impedance and low output impedance. It is extremely attractive for biomedical applications. The ion-sensing membrane plays an important role because the pH response of ISFET device is determined by sensing membrane. In the thesis, the hydrogenated amorphous silicon (a-Si:H) and amorphous tungsten oxide (a-WO3) thin films were used as the sensing membrane in order to investigate their pH responses. Although ISFET devices have the advantages mentioned-above, some non-ideal phenomena such as hysteresis, drift and temperature effect exist. For the sake of improving ISFET devices and being widely applied in the future, it is necessary to realize these non-ideal phenomena. Besides introducing the structure and theory of ISFET, drift, hysteresis and temperature effect will be studied and simulated. Drift behavior exists in the whole measurement, and hysteresis behavior is affected by slow response. These two properties limit the accuracy of ISFET. Furthermore, some characteristics such as pH sensitivity and drift are affected by operating temperature. In the thesis, the structure and theory (i.e., site-binding model) of ISFET will be introduced, then the pH sensitivity, time response, drift and hysteresis of a-Si:H ISFET and a-WO3 ISFET will be measured. Finally, we'll investigate the effects of operating temperature on other characteristic parameters of ISFET device.