Annealing effects of ZnO films deposited on (0001) Al₂O ₃ and (111) Si substrate by RF sputtering and GaN layer grown on ZnO films used as buffer layer by MOCVD

We investigated the crystal properties of ZnO deposited on (111) Si and c-Al₂O₃ substrates by RF sputtering with various thermal annealing temperatures and thick GaN layers grown on ZnO films used as buffer layer by MOCVD. To improve the quality of thick GaN films, we utilized LT-GaN buffer layers on ZnO/(111) Si and ZnO/c-Al₂O₃ substrates and investigated the effect of LT-GaN buffer layers on the properties of thick GaN. LT-GaN buffer layers were grown at 510 °C to 830 °C for 10 min. The crystalline and optical properties of thick GaN grown on ZnO/(111) Si and ZnO/c-Al₂O₃ substrate were affected by the LT-GaN buffer layer growth temperature.