Isotropic conduction and negative photoconduction in ultrathin PtSe$_2$ films

TL;DR

This study investigates the electrical and photoconductive properties of ultrathin PtSe$_2$ films used in FETs, revealing isotropic conduction, p-type behavior, and negative photoconductivity due to photogating effects.

Contribution

It demonstrates the isotropic electrical conduction and negative photoconductivity in ultrathin PtSe$_2$ films, providing insights into their optoelectronic behavior.

Findings

PtSe$_2$ exhibits p-type conduction with high hole mobility.

Electrical conduction is isotropic across different directions.

Negative photoconductivity occurs under laser irradiation due to photogating.

Abstract

PtSe$_2$ ultrathin films are used as the channel of back-gated field-effect transistors (FETs) that are investigated at different temperatures and under super-continuous white laser irradiation. The temperature-dependent behavior confirms the semiconducting nature of multilayer PtSe$_2$, with p-type conduction, a hole field-effect mobility up to 40 cm2/(Vs) and significant gate modulation. Electrical conduction measured along different directions shows isotropic transport. A reduction of PtSe$_2$ channel conductance is observed under exposure to light. Such negative photoconductivity is explained by a photogating effect caused by photo-charge accumulation in SiO$_2$ and at the Si/SiO$_2$ interface.