Deterministic Oxidation of Hafnium Diselenide Field-Effect-Transistors

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 (HfSe
₂
) materials, is emerging new material for electronic applications which is under represented. Here, we study mechanically exfoliated HfSe
₂
Field Effect Transistors (FET). We observe laser-induced HfSe
₂
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 HfSe
₂
channel. This technique can be used to engineer thin layers of dielectric with good contact to HfSe
₂
channel. We also characterize the electron transport of treated HfSe
₂
FET device. Although HfSe
₂
is an n-type material, we show that HfSe
₂
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 HfSe
₂
channel. Devices based on HfSe
₂
material can be promising for the future of electronic applications.