Electroless deposition of palladium films on gallium nitride for Schottky diodes

Abstract

This work presents electroless deposition of palladium films onto gallium nitride from aqueous palladium dichloride using sodium L-ascorbate as the reducing agent in an acidic bath. Profilometry, four-point probe measurements, energy dispersive x-ray spectroscopy (EDS), and x-ray photoelectron spectroscopy (XPS) were used to measure film thickness, sheet resistance, resistivity, morphology, and composition. The resistivity of Pd was 1-3 x 10 -5 Ω cm. Schottky diodes were produced from plated films, and the barrier heights and ideality factors were determined from current-voltage measurements. Average barrier heights were 1.13-1.26 eV, with ideality factors from 1.02-1.05, depending on the gallium nitride epilayer and substrate. Also presented is a method for depositing palladium-gallium alloy films onto gold surfaces from palladium dichloride and gallium (III) sulfate using sodium hypophosphite as the reducing agent; however, palladium-gallium alloys were not readily deposited on gallium nitride.