Low Temperature Synthesis of High Quality a Few PtSe2 Monolayers By Plasma Assisted Selenization Process

Abstract

Transition metal dichalcogenides (TMDs) receive a significant attention due to its intriguing properties for fundamental research and potential for application in electronics, catalysis, optoelectronics, and so on. In this work, we focus on growth of PtSe2 because of its chemical activity, small band gap and low resistivity. Recently, Yeliang Wang et al. 1 demonstrate single layer of PtSe2 by single crystal Pt substrate and selenization with 270 ºC. Despite in this case, the electrical properties of PtSe2 monolayer cannot be exploited due to the underneath Pt. It should be pointed that the synthesis temperature of PtSe2 is much lower compared with other TMDs such as MoS2 and WSe2. Besides, the electrical performance of PtSe2 is different from the other TMDs. Theoretical calculations of the band structure of PtSe2 shows large changes in the bandgap going from 1.3eV at the monolayer to 0.3 eV on bilayer and is expected a semi-metallic behavior at multiple PtSe2 monolayers. However, no experimental demonstration of the electrical properties has been explored so far. In our work, we try to grow PtSe2 by the plasma assisted selenization process. First, we deposit Pt metal on Si substrate by DC sputtering process within 5 nm thickness. After Pt deposition, we apply plasma assisted selenization to form a few PtSe2 monolayers at a temperature below 200 oC. Material characterization based on TEM, XPS and Raman analysis was applied to investigate the quality and the plasma effect on the resulting PtSe2 film. Moreover, we experimentally demonstrate the semiconducting properties of PtSe2and demonstrate the potential as a channel material for MOSFET applications.