Growth and characterization of alpha-, beta- and epsilon-phases of Ga2O3 using MOCVD and HVPE techniques

Heteroepitaxial films of Ga2O3 were grown on c-plane sapphire (0001). The stable phase beta-Ga2O3 was grown using the metal organic chemical vapor deposition technique, regardless of precursor flow rates, at temperatures between 500 degrees Cand 850 degrees C. Metastable alpha-and epsilon-phases were grown when using the halide vapor phase epitaxy (HVPE) technique, at growth temperatures between 650 degrees C and 850 degrees C, both separately and in combination. XTEM revealed the better lattice-matched a-phase g rowi ng se mi-cohe rently on the su bstrate, followed by epsilon-Ga2O3. The epitaxial relationship was determined to be [1100] epsilon-Ga2O3 parallel to [1120] alpha-Ga2O3 parallel to [1120] alpha-Al2O3. SIMS revealed that epilayers forming the epsilon-phase contain higher concentrations of Cl introduced during HVPE growth. [GRAPHICS] IMPACT STATEMENT This study demonstrates one of the first epitaxial growths of multiple polymorphs of Ga2O3 on sapphire (0001) substrates, including its beta-, alpha and epsilon-phases. Epitaxial relationship is confirmed through HRTEM.