Role of Process Parameters of Rapid Thermally Grown MoTe2 Thin Film for IR Detection

Abstract

In the field of electronic and optoelectronic applications, two-dimensional materials are found to be the promising candidates for futuristic devices. For the detection of infrared light, MoTe2 possesses an appropriate bandgap for which p-MoTe2/n-Si heterojunctions are suits well for photodetectors. In this study, rapid thermal technique is used to grow MoTe2 thin films on silicon (Si) substrates. Molybdenum (Mo) thin films were deposited using sputtering system on Si substrate and Tellurium (Te) film was deposited on Mo film by thermal evaporation technique. The substrates with Mo/Te thin films are kept in a face-to-face manner inside the RTP furnace. The growth was carried out at a base pressure of 2 torr with the flow of 160 sccm argon gas at different temperatures ranging from 400 °C to 700 °C. The XRD peaks appeared around 2θ = 12.8°, 25.5°, 39.2°, 53.2° corresponding to (002), (004), (006) and (008) orientation of hexagonal 2H-MoTe2 structure. The characteristic Raman peaks of MoTe2, observed at ~119 cm−1 and ~172 cm−1, corresponds to in-plane E1g and out-of-plane A1g mode of MoTe2, whereas the prominent peaks of the in-plane E1 2g mode at ∼234 cm−1, and the out-of-plane B1 2g mode at ∼289 cm−1 are also observed. RMS roughness is found to be increasing with increasing growth temperature. The bandgap of MoTe2 is calculated using Tauc plot and found to be 0.91 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 and 85.21 × 107 Jones for growth temperature of 600 °C and IR wavelength illumination of 1060 nm.