Interface effects of Schottky devices built from MoS₂ and high work function metals

Schottky junctions, formed by high work function metals and semiconductors, are important devices in electronics and optoelectronics. The metal deposition in traditional Schottky interfaces usually damages the semiconductor surface and causes defect states, which reduces the Schottky barrier height and device performance. This can be avoided in the atomically smooth interface formed by two-dimensional (2D) metals and semiconductors. For better interface tailoring engineering, it is particularly important to understand various interface effects in such 2D Schottky devices under critical or boundary conditions. Here we report the fabrication and testing of three types of MoS₂ devices, i.e., using PtTe₂, Cr and Au as contact materials. While the Cr/MoS₂ contact is an ohmic contact, the other two are Schottky contacts. The van-der-Waals interface of PtTe₂-MoS₂ results in a well-defined OFF state and a significant rectification ratio of 10⁴. This parameter, together with an ideality factor 2.1, outperforms the device based on evaporated Au. Moreover, a device in the intermediate condition is also presented. An abrupt increase in the reverse current is observed and understood based on the enhanced tunneling current. Our work manifests the essential role of doping concentration and provides another example for 2D Schottky interface design.