Highly Homogeneous 2D/3D Heterojunction Diodes by Pulsed Laser Deposition of MoS2 on Ion Implantation Doped 4H-SiC

Abstract

In this paper, 2D/3D heterojunction diodes have been fabricated by pulsed laser deposition (PLD) of MoS2 on 4H-SiC(0001) surfaces with different doping levels, i.e., n− epitaxial doping (≈1016 cm−3) and n+ ion implantation doping (>1019 cm−3). After assessing the excellent thickness uniformity (≈3L-MoS2) and conformal coverage of the PLD-grown films by Raman mapping and transmission electron microscopy, the current injection across the heterojunctions is investigated by temperature-dependent current–voltage characterization of the diodes and by nanoscale current mapping with conductive atomic force microscopy. A wide tunability of the transport properties is shown by the SiC surface doping, with highly rectifying behavior for the MoS2/n− SiC junction and a strongly enhanced current injection for MoS2/n+ SiC one. Thermionic emission is found the dominant mechanism ruling forward current in MoS2/n− SiC diodes, with an effective barrier ΦB = (1.04 ± 0.09) eV. Instead, the significantly lower effective barrier ΦB = (0.31 ± 0.01) eV and a temperature-dependent ideality factor for MoS2/n+ SiC junctions is explained by thermionic-field-emission through the thin depletion region of n+ doped SiC. The scalability of PLD MoS2 deposition and the electronic transport tunability by implantation doping of SiC represents key steps for industrial development of MoS2/SiC devices.