Comprehensive Temperature-Dependent DC Characterization of Organic Thin Film Transistor for Sensing Applications

This study presents a comparative analysis of the performance of a p-type (Pentacene) organic thin-film transistor (OTFT) for temperature sensing using organic and inorganic dielectrics (low-k dielectric and high-k dielectrics) such as PVA, SiO
₂
, and HfO
₂
in the saturation region of device operation. The device and the channel parameters such as mobility, threshold voltage, etc. are extracted using the conventional extraction approach at a temperature range of 293– 363 K. The simulation findings indicate how these characteristics change as a function of temperature, and hence could be employed in sensing applications. It is realized that the optimum performance is shown by the high-k dielectric (HfO
₂
), where the mobility is
$\sim \,\,4.25\times 10^{-3}$
cm
²
/Vs, a low subthreshold slope of 59.6 mV/decade, a high ON/OFF ratio close to
$9.4\times 10^{16}$
, low contact resistance of 1.1
$\text{G}{\Omega }$
and threshold voltage (
$\text{V}_{{\mathrm {TH}}}$
) decreases linearly (positive shift) with increasing temperature. The low value of
$\text{V}_{{\mathrm {TH}}}$
ensures low operating voltage thus enabling the realization of a low power temperature sensor. It is shown that there is a 10
⁴
percentage change in the ON/OFF ratio which leads to the conclusion that the ON/OFF ratio can be a deciding factor in determining the optimum device parameter for sensing applications. Apart from this, the threshold voltage and the subthreshold slope (SS) are also equally important that affect the performance of the sensors. Notably, the temperature coefficient which denotes the change in device parameter per degree change in temperature is calculated for a more comprehensive study. It is observed that the temperature coefficient for drain current is
$11.8\times 10^{-3}$
ng a large change in electrical characteristics when the temperature is altered by 1 kelvin.