Tuning of zinc oxide temperature sensing and optical absorption properties by tin heavy-doping

Abstract

This paper presents the feasibility of tin (Sn) heavily doped zinc oxide (ZnO) thin film as an active layer for a microbolometer and the effect of this Sn heavily doping on the structural, optical and electrothermal properties of Sn-doped ZnO (SnxZn1-xO) thin films. The SnxZn1-xO thin films were deposited on substrates using an RF/DC co-sputtering method at room temperature with different Sn dopant concentrations %, x (x = 0.22, 0.26 and 0.32). It was found that the optical and electro-thermal properties were strongly affected by Sn doping. The result revealed an increase in the visible and infrared radiation absorption and electrical conductivity with increasing Sn doping whereas the temperature coefficient of resistance (TCR) decreases. A maximum TCR value of 1.9%/K with a sheet resistance (Rs) of 233 kΩ/□ was observed with 0.22 Sn doping concentration. The result proved that the Sn doping could help to decrease the TCR temperature dependence and the sheet-resistance of ZnO thin film as well as increasing its IR radiation absorption that makes it a strong candidate for the active layer of microbolometer.