Fabrication of MoS2thin films by sulphonation of sputtered Mo thin films

Abstract

Minimization of conventional semiconductor materials is hindered due to the defects and un controlable bandgap variation. To address these issues, 2Dtransition metaldichalcogenides(TMDC) has been explored rapidly. Among the discovered TMDCs, molybdenum disulphide(MoS2) has gained attention due to their remarkable structural ,optical , electrical and mechanical properties, which makes it a suitable candidate for the future electronic and optoelectronic devices. In this work, molybdenum(Mo) thin films were deposited on cleaned silicon substrates by RF sputtering technique at a power of 100W for 30sec. A layer of sulphur was deposited using thermal evaporation technique. Thereafter, two sulphur coated Mo/Si samples were kept facing each other inside a rapid heat treatment furnace. The samples were treated at 800 °C for 5 mins in Ar+H2 ambient. The structural and optical properties of MoS2 layers were studied by X-Ray diffraction, Raman and PL spectroscopy. In order to carry out the electrical measurements, MoS2/Si p-n heterojunction was fabricated. The junction and semiconductor properties were evaluated by current-voltage and capacitance-voltage measurements. In order to evaluate the sensing property of MoS2 thin films, a detector setup based on Arduino UNO micro-controller is designed. The hardware setup is associated with a LED (light emitting diode) detector and GSM (Global System for Mobile) unit, which sends a message when the measured current exceeds the threshold value.