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

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.