Modification of electrical properties of amorphous vanadium oxide (a-VOx) thin film thermistor for microbolometer

Abstract

This work reports on the modification of electrical properties of amorphous vanadium oxide (a-VOx) thin film thermistor by growth temperature and its effects on the performances of a cooler-free microbolometer. The a-VOx thin films have been deposited by pulsed DC sputtering processes under various growth temperatures from 160 to 230 degrees c. The sheet resistance of the samples at room temperature decreases from 330 to 70 k Omega/square with increasing growth temperature. This is due to the increase of oxygen vacancies at higher growth temperature, which have been confirmed by XPS analysis. Temperature dependence of resistance of a-VOx films shows non-hysteresis behaviors up to 120 degrees c, which in turn shows clear activation energies. The activation energy of a-VOx films also decreases from 0.190 to 0.145 eV with increasing growth temperature, which confirms the decrease of temperature coefficient of resistance (TCR) from 2.80 to 2.44 (-%/K) at 25 degrees c and from 1.48 to 1.14 (-%/K) even at 120 degrees c. The responsivities of fabricated microbolometers based on the a-VOx thin film thermistors have been measured from 3.04 x 10(3) to 1.14 x 10(3) VA/k/ at room temperature and from 9.54 x 10(2) to 3.02 x 10(2) VFW even at 120 degrees C with increasing growth temperature. (C) 2022 Published by Elsevier B.V.