Deterministic Oxidation of Hafnium Diselenide Field-Effect-Transistors

Abstract

Transition Metal Dichalcogenides (TMDCs) materials have been under research for the past decade, mainly due to their exceptional optical, thermal, and electrical characteristics. Hafnium Diselenide (HfSe2) materials, is emerging new material for electronic applications which is under represented. Here, we study mechanically exfoliated HfSe2 Field Effect Transistors (FET). We observe laser-induced HfSe2 oxide peak in ambient environment. Our results show that this new oxide Raman peak changes with treatment exposure time, which enables us to control the formation of oxide layers on the surface of HfSe2 channel. This technique can be used to engineer thin layers of dielectric with good contact to HfSe2 channel. We also characterize the electron transport of treated HfSe2 FET device. Although HfSe2 is an n-type material, we show that HfSe2 can exhibit anomalous p-type behavior after electrically heating the device. The underlying mechanism behind this phenomenon is still not clear, but one possible reason is oxide-induced doping of HfSe2 channel. Devices based on HfSe2 material can be promising for the future of electronic applications.