Effects of Se substitution on the Schottky barrier of a MoS x Se(2−x)/graphene heterostructure

Abstract One of the most fundamental and challenging tasks to achieve high-performance ultra-thin atomic field effect transistors (FETs) is to obtain very low or even zero Schottky barrier height (SBH) at source/drain contact. Here, we propose that heteroatom substitution is an effective strategy to tune the performance of two-dimensional materials-based FETs, which is demonstrated by systematically exploring the effects of Se substitution on the structural and electronic properties, and SBH of MoS x Se (2− x ) /graphene (MoS x Se (2− x ) /G) heterostructures using first-principles calculations. Our findings suggest that the type and height of Schottky barrier can be adjusted by varying Se concentration. The transformation from n-type Schottky barrier to p-type Schottky barrier can be realized when the Se concentration is greater than 25%. With the increase of Se concentration, a lower p-type Schottky barrier can be obtained at the interface to achieve efficient charge transfer. Moreover, the Schottky barrier of MoS x Se (2− x ) /G heterostructures with different Se concentration would disappear as the external electric field exceeds certain values. These results would provide a direction in developing high-performance FETs involving heteroatom substitution layers as contact electrodes.