Temperature Dependent Current-Voltage Characteristics of Pt/MoS2 Schottky Junction

Abstract

AbstractMolybdenum disulphide (MoS2) is one of the transition metal dichalcogenide (TMD) materials which has attracted attention due to its various interesting properties. MoS2 is very promising for electronic and optoelectronic devices due to its indirect band gap (∼1.2 eV) for few layer and direct band gap (∼1.8 eV) for monolayer MoS2. In MoS2 based Schottky devices, Schottky barrier height depends on the thickness of MoS2 because of its tunable electronic properties. Here, we have used DC sputtering technique to fabricate metal-semiconductor junction of MoS2 with platinum (Pt) metal contacts. In this work, MoS2 thin film (∼10 nm) was deposited on p-Silicon (111) using DC sputtering technique at optimized parameters. Schottky metallization of Pt metal (contact area ∼ 0.785x10-2 cm2) was also done using DC sputtering. Current-voltage (I-V) characteristics of the Pt/MoS2 Schottky junction have been investigated in the temperature range 80-350K. Forward I-V characteristics of Pt/MoS2 junction are analysed to calculate different Schottky parameters. Schottky barrier height increases and ideality factor decreases on increasing the temperature from 80-350K. The I-V-T measurements suggest the presence of local inhomogeneities at the Pt/MoS2 junction. Schottky barrier inhomogeneities occur in case of rough interface. In such cases, the Schottky barrier height does not remain constant and vary locally. Current transport through the Schottky junction is a thermally activated process. As temperature increases, more and more electrons overcome the spatially inhomogeneous barrier height. As a result, the ideality factor becomes close to unity and apparent barrier height increases due to increase in temperature.