Effect of Temperature and Humidity on $\hbox{NO}_{2}$ and $\hbox{NH}_{3}$ Gas Sensitivity of Bottom-Gate Graphene FETs Prepared by ICP-CVD

Graphene was used for a sensing part of bottom-gate field-effect transistor (FET)-type gas sensors, and the sensing performance of the sensors was studied. We investigated the effect of temperature
$(T)$
and relative humidity on the gas sensitivity of bottom-gate graphene FETs prepared by the inductively coupled plasma chemical vapor deposition method. The conductivity change of graphene exposed to nitrogen oxide
$(\hbox{NO}_{2})$
and ammonia
$(\hbox{NH}_{3})$
was increased with increasing temperature and humidity. For
$\hbox{NO}_{2}$
gas, the graphene FET shows increasing
$I_{D}$
with increasing
$T$
and also increasing
$I_{D}$
with increasing humidity. However, the FET shows an opposite trend with the
$T$
and humidity for
$ \hbox{NH}_{3}$
gas.