Synthesis of Mos2 Thin Films by Sulphonation of Sputtered Mo Thin Films

Abstract

MoS2 has a great deal of interest among the semiconductor group of researchers, due to the unique electronic and optoelectronic properties like, finite bandgap, low static power consumption. In this work an attempt has been made to develop a CMOS compatible process for the fabrication of a homogeneous MoS2 thin film. A two step synthesis process was adopted. In the first step, Molybdenum (Mo) thin film was deposited on silicon substrate by RF magnetron sputtering technique. The sputtering was carried out at RF power of 45W with the working pressure as 5 x 10-3 mbar. In, the second step synthesis of MoS2 was obtained by sulphonation of Mo thin films using the custom designed two heating zone tubular CVD system. The sulphonation was carried out by keeping the Mo thin films at heating zone-I (800 °C) and sulphur powder in the heating zone-II (120°C) with flow of hydrogen and argon gas in 1:10 ratio. A uniform surface morphology of MoS2 thin films was observed from the FESEM image. The optical properties were studied using Raman and photoluminescence spectroscopy. Two characteristics Raman peaks, observed at 386 cm-1 and 408 cm-1, confirms the formation of MoS2 film, which corresponds to the hexagonal coordination (2H). The prominent photoluminescence peak corresponds to the photon energy of 1.75eV, which can be attributed to the optical bandgap of MoS2. The MoS2 layer fabricated can be potential candidate for the fabrication of heterostructure based future electronic and optoelectronic devices.