Electron irradiation of multilayer PdSe2 field effect transistors

Palladium diselenide (PdSe2) is a recently isolated layered material that has attracted a lot of interest for its pentagonal structure, air stability and electrical properties that are largely tunable by the number of layers. In this work, multilayer PdSe2 is used as the channel of back-gate field-effect transistors, which are studied under repeated electron irradiations. Source-drain Pd electrodes enable contacts with resistance below 350k Omega mu m. The transistors exhibit a prevailing n-type conduction in high vacuum, which reversibly turns into ambipolar electric transport at atmospheric pressure. Irradiation by 10 keV electrons suppresses the channel conductance and promptly transforms the device from n-type to p-type. An electron fluence as low as 160 e(-)/nm(2) dramatically changes the transistor behavior, demonstrating a high sensitivity of PdSe2 to electron irradiation. The sensitivity is lost after a few exposures, with a saturation condition being reached for fluence higher than similar to 4000 e(-)/nm(2). The damage induced by high electron fluence is irreversible as the device persists in the radiation-modified state for several hours, if kept in vacuum and at room temperature. With the support of numerical simulation, we explain such a behavior by electron-induced Se atom vacancy formation and charge trapping in slow trap states at the Si/SiO2 interface.