Electron irradiation on multilayer PdSe2 field effect transistors

Palladium diselenide (PdSe2) is a recently isolated layered material that has attracted a lot of interest for the pentagonal structure, the air stability and the electrical properties largely tunable by the number of layers. In this work, PdSe2is used in the form of multilayer as the channel of back-gate field-effect transistors, which are studied under repeated electron irradiations. Source-drain Pd leads enable contacts with resistance below 350 kΩ·μm. 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-/nm2dramatically change the transistor behavior demonstrating a high sensitivity of PdSe2to electron irradiation. The sensitivity is lost after few exposures, a saturation condition being reached for fluence higher than ∼4000 e-/nm2. The damage induced by high electron fluence is irreversible as the device persist 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/SiO2interface.