Growth and characterization of α-, β-, and ϵ-phases of Ga2O3 using MOCVD and HVPE techniques

ABSTRACTHeteroepitaxial films of GaO were grown on c-plane sapphire (0001). The stable phase β-GaO was grown using the metalorganic chemical vapor deposition technique, regardless of precursor flow rates, at temperatures between 500C and 850C. Metastable α- and ϵ-phases were grown when using the halide vapor phase epitaxy (HVPE) technique, at growth temperatures between 650C and 850C, both separately and in combination. XTEM revealed the better lattice-matched α-phase growing semi-coherently on the substrate, followed by ϵ-GaO. The epitaxial relationship was determined to be [] ϵ-GaO [] α-GaO [] α-AlO. SIMS revealed that epilayers forming the ϵ-phase contain higher concentrations of Cl introduced during HVPE growth.