Inclined ITO thin film with thermoelectric anisotropy: A promising sensitivity material for ultraviolet pulsed photodetector based on light-induced transverse voltage effect

Abstract

Indium tin oxide (ITO) thin film, a typical transparent conductive oxide, is usually used as a material for thin film thermocouples due to its large Seebeck coefficient and low resistivity. In this work, inclined epitaxial ITO thin films have been prepared on c-axis miscut YSZ (001) single crystal substrates. The distinct response voltages, oriented perpendicular to the temperature gradient, are detected based on the light-induced transverse voltage (LITV) effect, originating from the anisotropic Seebeck coefficient ΔS between the ab-plane and c-axis of ITO thin films. Following the high-temperature annealing process, ITO thin films experience a significant increase in ΔS by an order of magnitude, thereby amplifying the response voltage. The voltage amplitudes have a good linear relationship with the inclined angles (sin2α). Moreover, under the irradiation of a 248 nm pulsed laser, the response voltage exhibited a fast response time with a rise time τr of 20∼26 ns and decay time τd of 18∼24 ns due to the intrinsic characteristic of low resistivity, demonstrating its potential to be a candidate material for fast response self-powered ultraviolet photodetector.