Role of growth temperature on microstructural and electronic properties of rapid thermally grown MoTe2 thin film for infrared detection

Abstract In the field of electronic and optoelectronic applications, two-dimensional materials are found to be promising candidates for futuristic devices. For the detection of infrared (IR) light, MoTe 2 possesses an appropriate bandgap for which p-MoTe 2 /n-Si heterojunctions are well suited for photodetectors. In this study, a rapid thermal technique is used to grow MoTe 2 thin films on silicon (Si) substrates. Molybdenum (Mo) thin films are deposited using a sputtering system on the Si substrate and tellurium (Te) film is deposited on the Mo film by a thermal evaporation technique. The substrates with Mo/Te thin films are kept in a face-to-face manner inside the rapid thermal-processing furnace. The growth is carried out at a base pressure of 2 torr with a flow of 160 sccm of argon gas at different temperatures ranging from 400 °C to 700 °C. The x-ray diffraction peaks appear around 2 θ = 12.8°, 25.5°, 39.2°, and 53.2° corresponding to (002), (004), (006), and (008) orientation of a hexagonal 2H-MoTe 2 structure. The characteristic Raman peaks of MoTe 2 , observed at ∼119 cm −1 and ∼172 cm −1 , correspond to the in-plane E 1g and out-of-plane A 1g modes of MoTe 2 , whereas the prominent peaks of the in-plane E 1 2g mode at ∼234 cm −1 and the out-of-plane B 1 2g mode at ∼289 cm −1 are also observed. Root mean square (RMS) roughness is found to increase with increasing growth temperature. The bandgap of MoTe 2 is calculated using a Tauc plot and is found to be 0.90 eV. Electrical characterizations are carried out using current–voltage and current–time measurement, where the maximum responsivity and detectivity are found to be 127.37 mA W −1 and 85.21 × 10 7 Jones for a growth temperature of 600 °C and an IR wavelength illumination of 1060 nm.