Extraction of Schottky diode parameters and electron transport and dielectric relaxation in PdSe2 nanoflakes

Abstract

Palladium diselenide (PdSe₂) exhibits a unique anisotropic electronic behavior, high carrier mobility, and layer-dependent indirect-to-direct bandgap transition, positioning it as a versatile material for next-generation 2D device architectures. In this work, we investigated the electrical properties and conduction and relaxation mechanisms of mechanically exfoliated PdSe₂ flakes. Raman spectroscopy and AFM were employed to confirm the purity and thickness of the sample. Electrical characterizations, including current–voltage (I–V) measurements and complex impedance spectroscopy (CIS) were performed, revealing crucial information about charge carrier transport mechanisms, contact behavior, and resistive properties. For contact-limited conduction mechanisms, Schottky emission was investigated, and the thermionic emission model was employed to determine the Schottky diode parameters, along with a re-evaluation of Richardson's constant. In bulk-limited conduction mechanisms, the Poole–Frenkel (PF) emission was ascertained with a determination of the dielectric constant. To gain insights into the relaxation mechanisms, complex impedance spectroscopy, complex dielectric permittivity, and complex modulus spectroscopy analyses were conducted. A switching ratio of ∼10² was achieved, indicating the suitability of PdSe₂ for applications in memory devices, neuromorphic computing, and sensing technologies.