Esaki Diode Behavior in Highly Uniform MoS2/Silicon Carbide Heterojunctions

Abstract

The heterogeneous integration with 2D materials enables new functionalities and novel devices in state-of-the-art bulk (3D) semiconductors. In this work, highly uniform MoS2 heterostructures with silicon carbide (4H-SiC) are obtained by a facile synthesis method, highly compatible with semiconductor fab processing, i.e., the sulfurization of predeposited very-thin (≈1.2 nm) Mo films at a temperature of 700 °C. Current–voltage characteristics of MoS2/n+-4H-SiC junctions collected by conductive atomic force microscopy show a pronounced negative differential resistance even at room temperature, which is a typical manifestation of band-to-band tunneling between degenerately p+-/n+-doped semiconductors. Here, the degenerate p+-type doping of MoS2, with Nholes ≈ 4 × 1019 cm−3 evaluated by Raman mapping, is ascribed to the significant MoO3 content in the film, as demonstrated by X-ray photoelectron spectroscopy analyses. Furthermore, atomic resolution transmission electron microscopy analyses reveal the presence of an ultrathin (≈1 nm) SiO2 tunneling barrier between MoS2 and 4H-SiC, formed during the sulfurization process. The observation of Esaki diode behavior in MoS2 heterojunctions with 4H-SiC opens new perspectives for this material system as a platform for ultrafast low-power consumption digital applications.