Low resistance metal contacts on MoS2 films deposited by laser physical vapor deposition

Abstract

Niobium doped MoS2 films were grown on sapphire and SiO2-p-Si substrates by laser physical vapor deposition at 600 °C. The nature of conductivity in MoS2 film on sapphire was found to be n-type while that in the film on SiO2-p-Si was p-type. Metal contacts with Al, Mo, Ta and Au were deposited by laser physical deposition on the MoS2 films. Applied current versus voltage measurements were made at room temperature. In addition, applied voltage versus current measurements were made as a function of temperature from 270 to 400 K. The two sets of measurements were used to determine the ideality factor, series resistance and Schottky barrier height for the four metal contacts. Lower resistance contacts were found to form with Ta and Mo for n-type films on sapphire and with Al and Mo for p-type films on SiO2-p-Si. The value of Schottky barrier height for the four metal films on SiO2-p-Si remained closer but differed for films on sapphire. The Schottky barrier height was found to increase with applied voltage indicating the influence of interface states and defects present in the films.