Growth of epitaxial GaN on LiGaO2 substrates via a reaction with ammonia

Abstract

Oriented GaN and LixGa(2−x)O2xN2(1−x) thin films were found to grow on LiGaO2 single-crystal (001) substrates via a reaction between ammonia (or reactive ammonia species) and substrate components at temperatures between 700 and 1000 °C. The compound LixGa(2−x)O2xN2(1−x), where x was determined to be ≈0.35, is a solid solution formed from a partial reaction of ammonia with the LiGaO2 substrate. Negligible lithium (i.e., x ≈ ≈ 0) was detected in the films formed with a constant high flow rate (164 cm3/min) of ammonia, indicating a complete reaction with the LiGaO2 single crystal. The growth of a partial surface film and surface pitting suggests a vapor reaction (via loss of LiNH2 or LiOH, and nitridation of Ga2O) similar to that observed when semiconductor grade reacts with N2 to form Si3N4. The resultant films have either a wurtzite structure or one approaching the wurtzite structure. Both films form on the substrate with the same orientation as the LiGaO2.