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 350kΩµm. The transistors exhibit a prevailing n-type conduction in high vacuum, which reversibly turns into ambipolar electric transport at atmospheric pressure. Irradiation by 10keV electrons suppresses the channel conductance and promptly transforms the device from n-type to p-type. An electron fluence as low as 160e^–/nm² 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 ∼4000e^–/nm². 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.