A Study on Gas Sensor Applications of Suspended-Nanowire-Channel TFTs and the Characterization of Suspended-Gate Vertical-MOSFETs

• Main Authors: Wang, Chung-Ming, 王崇名
• Other Authors: Lin, Horng-Chih
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/37696660453981582274

碩士 === 國立交通大學 === 電子研究所 === 99 === In this thesis, we have successfully fabricated two kinds of devices including the suspended-NW-channel TFTs and the SG vertical-MOSFETs. The sidewall spacer NW in suspended-NW-channel TFTs and the sidewall spacer gate electrode in the vertical channel of SG vertical-MOSFETs are both formed by a simple anisotropic plasma etching technique. We have successfully applied the suspended-NW-channel TFT to gas sensor application. In the environments containing ammonia (NH3), the basic electrical characteristics of the suspended-NW-channel TFT are changed with the variation in the concentration of NH3. The shift in threshold voltage (Vth) or the change of drain current (ID) with varying NH3 concentration can be used as an indicator to sense the NH3. The possible reaction mechanisms between NH3 molecules and nanowire surface are discussed and analyzed. Besides, we have also successfully improved the undesirable two-step turn-on phenomenon encountered in the characterization of SG vertical-MOSFETs conducted in a previous work by changing the mask layout, and studied the basic electrical characteristics of the newly designed and fabricated SG vertical-MOSFETs. Finally, we have successfully removed the sacrificial oxide layer to suspend the side gate and studied the characteristics of the devices.