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

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 (approximate to 10(16) cm(-3)) and n(+) ion implantation doping (>10(19) cm(-3)). After assessing the excellent thickness uniformity (approximate to 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 phi(B) = (1.04 +/- 0.09) eV. Instead, the significantly lower effective barrier phi(B) = (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.

Automated summary

In this study, 2D/3D heterojunction diodes were fabricated using pulsed laser deposition. The doping levels of SiC surfaces were varied to investigate the transport properties of MoS2. The results showed that surface doping of SiC can significantly influence the current injection across the heterojunctions, resulting in highly rectifying behavior and enhanced current injection. The dominant mechanisms governing current flow were identified, and the effective barriers for different contacts were determined.