Tunable Electron Transport in Defect-Engineered PdSe<sub>2</sub>
Tanima Kundu, Barnik Pal, Bikash Das, Rahul Paramanik, Sujan Maity, Anudeepa Ghosh, Mainak Palit, M. Kopciuszyński, Alexei Barinov, Sanjoy Kr Mahatha, Subhadeep Datta
Abstract
Tuning the ambipolar behavior in charge carrier transport via defect-engineering is crucial for achieving high mobility transistors for nonlinear logic circuits. Here, we present the electric-field tunable electron and hole transport in a microchannel device consisting of highly air-stable van der Waals (vdW) noble metal dichalcogenide (NMDC), PdSe 2, as an active layer. Pristine bulk PdSe 2 constitutes Se surface vacancy defects created during the growth or exfoliation process and offers ambipolar transfer characteristics with a slight electron dominance recorded in field-effect transistor (FET) characteristics showing an ON/OFF ratio <10 and electron mobility ∼21 cm 2 /(V·s). However, transfer characteristics of PdSe 2 can be tuned to a hole-dominated transport while using hydrochloric acid (HCl) as a p -type dopant. On the other hand, the chelating agent EDTA, being a strong electron donor, enhances the electron-dominance in PdSe 2 channel. In addition, p -type behavior with a 100 times higher ON/OFF ratio is obtained while cooling the sample down to 10 K. Low-temperature angle-resolved photoemission spectroscopy resembles the p -type band structure of PdSe 2 single crystal. Also, first principle density functional theory calculations justify the tunability observed in PdSe 2 as a result of defect-engineering. Such a defect-sensitive ambipolar vdW architecture may open up new possibilities toward future CMOS (Complementary Metal-Oxide-Semiconductor) device fabrications and high performance integrated circuits.