Role of vacancies in tuning the electronic properties of Au-MoS2 contact

Abstract

Understanding the electronic properties between molybdenum disulfide (MoS2) and metal electrodes is vital for the designing and realization of nanoelectronic devices. In this work, influence of intrinsic vacancies in monolayer MoS2 on the electronic structure and electron properties of Au-MoS2 contacts is investigated using first-principles calculations. Upon formation of vacancies in monolayer MoS2, both tunnel barriers and Schottky Barriers between metal Au and monolayer MoS2 are decreased. Perfect Au-MoS2 top contact exhibits physisorption interface with rectifying character, whereas Au-MoS2 contact with Mo-vacancy shows chemisorption interface with Ohmic character. Partial density of states and electron density of defective Au-MoS2 top contacts are much higher than those of perfect one, indicating the lower contact resistance and higher electron injection efficiency of defective Au-MoS2 top contacts. Notably, Mo-vacancy in monolayer MoS2 is beneficial to get high quality p-type Au-MoS2 top contact, whereas S-vacancy in monolayer MoS2 is favorable to achieve high quality n-type Au-MoS2 top contact. Our results provide guidelines for designing and fabrication of novel 2D nanoelectronic devices.