Transparent Conductive Electrodes of β-Ga2O3/Ag/β-Ga2O3 Multilayer for Ultraviolet Emitters

We investigated the optical and electrical properties of a beta-Ga2O3/Ag/beta-Ga2O3 multilayer transparent conductive electrode deposited on an beta-Al2O3 (0001) substrate. For the deposition of a continuous Ag layer, we preliminarily performed anultraviolet-ozone pretreatment of the Ga2O3 bottom layer. To obtain a stable beta-phase of Ga2O3, the beta-Ga2O3/Ag/beta-Ga2O3 multilayer was annealed at 700 degrees C under N-2 atmosphere. The transmittance and sheet resistance of the beta-Ga2O3/Ag/beta-Ga2O3 multilayer were critically affected by the surface morphology and thickness of the Ag interlayer. The multilayer with optimized thicknesses (beta-Ga2O3 top layer: 30 nm; Ag interlayer: 12 nm; beta-Ga2O3 bottom layer: 60 nm) exhibited a resistance of 8.48 Omega sq(-1), an average optical transmittance of 87.16% in the ultraviolet wavelength range from 300 to 350 nm, and a figure of merit of 29.81 x 10(-3) Omega(-1).