Near room temperature, SMT and visible photo-response in pulsed laser deposited VO2 (M1) thin films

Abstract

Vanadium oxides attracted much attention during the last decades for their distinctive optical, electrical, and physical properties. Due to such unique properties, vanadium oxide has various potential applications in the field of microelectronics, sensors, Micro Electro Mechanical Systems (MEMS), and smart windows. In this study, the vanadium oxide thin films have been deposited on silicon substrates at different substrate temperatures using Pulsed Laser Deposition (PLD). The morphological, structural, electrical, and optical properties of the deposited films were examined using Scanning Electron Microscope (SEM), X-ray Diffraction (XRD), Four Probe Measurements, and Fourier Transform Infrared Spectrometry (FTIR). It is demonstrated that the vanadium oxide VO2 (M1) thin films deposited at higher substrate temperature showed a Semiconductor to Metal (SMT) transition. The SMT temperature in VO2 (M1) thin films deposited at 550 °C and 600 °C substrate temperatures are related to the lattice strain. Moreover, it is suggested that the p-Si and n-VO2 form a type-III heterojunction. The n-VO2/p-Si heterojunction device showed a large room-temperature photo-response to the 670 nm laser operating at 5 mW under reverse biased conditions. Contrary to conventional photodetectors, VO2 (M1) thin films formed a self-powered photodetector with short-circuit current (Isc) of ∼3 μA and an open-circuit voltage (Voc) of ∼ 120 mV.