Solution-processed epitaxial PdRhO2 metallic films as Schottky electrodes

Abstract

Metallic delafossite PdRhO2 thin films were synthesized using a low-rhodium solution deposition strategy, achieving epitaxial growth despite a significant lattice mismatch. Comparative structural and electrical transport analyses demonstrate that reducing the lattice mismatch significantly improves both film quality and electrical performance. First-principles calculations reveal that the metallic conductivity in PdRhO2 originates primarily from Pd-derived states and their hybridization with Rh 4d orbitals at the Fermi level. Furthermore, a PdRhO2/β-Ga2O3 Schottky heterojunction was fabricated, exhibiting a rectification ratio on the order of ∼109 and a Schottky barrier height of 1.13 ± 0.06 eV. This barrier height exceeds the prediction of the Schottky–Mott rule, which is attributed to a naturally formed interfacial dipole layer. These findings offer a cost-effective pathway to epitaxial Rh-based thin films and highlight their potential for application in electronic integrated circuits.