An Investigation on the Device Mechanism in a CO2 Sensing Microdiode Based on WO3 and IrO2

• Main Authors: Chen, Ranyi, 陳瓀懿
• Other Authors: Shuchi Chao
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/02445507873286146780

碩士 === 國立交通大學 === 電子物理學系 === 85 === We have sputtered WO3 and IrO2 thin films on individual Pt electrodes.Part of the films were stacked and the films were coated with a polymer electrolyte（PVA/KHCO3）. This device can function as an optical/electrical switch/diode at 1 atm and room temperature. When configured as a CO2 sensing microdiode, the current in the diodes tend to fall mostly with occasional rises in some devices. We investigated this current behavior in three experiments in the hope to disclose its mechanism. They showed that：（1）The potential shift in IrO2 under CO2（which increases the H+ concentration in the electrolyte）is larger than that in WO3, therefore causing the current to fall normally.（2）When we shielded the IrO2 side with epoxy, the current tends to rise, opposite to that observed when the WO3 side is shielded instead. This means that we can control the trend in sensing current change by this one-sided shielding technique.（3）The film thickness has an impact on the trend in the current change. The distribution of voltage in the diode can be established by modelling the voltage drop to explain the current mechanism.（4）We can confirm the above current mechanism by measuring the transmittance change in the films to corroborate our results.