Summary: | 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.
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