Pressure-Tunable Ambipolar Conduction and Hysteresis in Ultrathin Palladium Diselenide Field Effect Transistors

A few-layer palladium diselenide (PdSe2) field effect transistor is studied under external stimuli such as electrical and optical fields, electron irradiation and gas pressure. We observe ambipolar conduction and hysteresis in the transfer curves of the PdSe2 material unprotected and as-exfoliated. We tune the ambipolar conduction and its hysteretic behavior in the air and pure nitrogen environments. The prevailing p-type transport observed at room pressure is reversibly turned into dominant n-type conduction by reducing the pressure, which can simultaneously suppress the hysteresis. The pressure control can be exploited to symmetrize and stabilize the transfer characteristic of the device as required in high-performance logic circuits. The transistor is immune from short channel effects but is affected by trap states with characteristic times in the order of minutes. The channel conductance, dramatically reduced by the electron irradiation during scanning electron microscope imaging, is restored after several minutes anneal at room temperature. The work paves the way toward the exploitation of PdSe2 in electronic devices by providing an experiment-based and deeper understanding of charge transport in PdSe2 transistors subjected to electrical stress and other external agents.