Demonstration of CuI as a P–N heterojunction to β-Ga2O3

Abstract

Vertical heterojunction p-CuI/n-Ga2O3 diodes were fabricated on commercial β-Ga2O3 substrates using the reaction of epitaxially-sputtered Cu with natural I2 vapor at room temperature followed by either a high temperature I2 gas reaction or an I2 solution treatment to remove iodine vacancies. Results show that using an epitaxially-oriented over a polycrystalline Cu layer produces larger and more strongly bonded CuI crystals. Hall and current–voltage measurements support rectifying behavior consistent with p-CuI/n-Ga2O3 heterojunction characteristics including 8 orders of magnitude Ion/Ioff ratio and an ideality factor of 1.37 measured on the sample with the lowest concentration of iodine vacancies.