Analysis of the relationship between the contact barrier and rectification ratio in a two-dimensional P–N heterojunction

The excellent performance of electronic and optoelectronic devices based on two-dimensional materials, including graphene and transition metal dichalcogenides (TMDs) such as MoS2 and WSe2, has inspired enthusiastic research on their potential applications in many fields. Numerous studies have been done on van der Waals heterojunctions, but a full understanding of the relationship between the contact barrier and the rectification ratio in these structures is still uncertain. In this work, we investigate the electrical properties of a lateral P–N junction based on an MoS2 and WSe2 heterojunction and extract the Schottky barrier heights in the contact areas. The barrier heights extracted from the device for MoS2-metal, WSe2-metal and P–N junction, are 71.6 meV, 232.7 meV, and 30.9 meV respectively. The result indicates that the rectification ratio of a lateral P–N junction mainly comes from the Schottky barrier between WSe2 and metal, which is distinct from traditional P–N junctions based on silicon. Our work quantitatively analyzes the effect of the contact barrier and the P–N junction on the electrical characteristics of the rectification ratio, which provides a deep understanding of the electronic transport characteristics of P–N heterojunctions and paves the way for the construction of novel electronic devices based on van der Waals heterojunctions in the future.