Giant laser-induced thermoelectric voltage in <i>c</i>-axis inclined Na<sub>x</sub>CoO<sub>2</sub> thin films

Abstract

ABSTRACT In this paper, we have prepared c-axis inclined Na x CoO 2 thin films on 10 o and 20 o tilted c-Al 2 O 3 substrates and studied its light-induced thermoelectric voltage effect by using an ultraviolet pulsed laser as light source. A giant open-circuit voltage signal with the peak voltage V p of tens of voltage was observed when th e film surface was illuminated by the 308 nm pulsed radiation, and the V p increased linearly with the inclination angle as well as the laser energy on the film. In addition, we found that Ag doping in Na x CoO 2 films can improve the sensitivity of the thermoelectric voltage signal. The results demonstrate that c-axis inclined Na x CoO 2 thin film has a great potential application in the detection of weak ultraviolet pulsed radiation. Keywords: Laser-induced thermoelectric voltage, Na x CoO 2 thin films, Ag doping, photodetector 1. INTRODUCTION In the past decades, light-induced thermoelectric voltage (LITV) effect in the transition metal oxide thin Þ lms grown on tilted substrates or artificially created tilted metallic multilayers have been extensively studied due to its great potential applications in photodetectors