Investigation of growth dynamics of β-Ga2O3 LPCVD by independently controlling Ga precursor and substrate temperature

We present results on low-pressure chemical vapor deposition (LPCVD) of b-Ga2O3 on a c-sapphire substrate with independent control of Ga precursor (T-P) and substrate (T-SUB) temperatures, allowing independent tuning of the Ga flux and thermal energy of the adatoms on the substrate surface. Experiments with constant T-P +/- 900 degrees C with varying T-SUB (600 degrees C-1050 degrees C) and varying T-P (800 degrees C-1000 degrees C) with constant T-SUB = 900 degrees C are reported. Island/nanorod formation on top of b-Ga2O3 thin film was observed at T-SUB = 600-750 degrees C, suggesting the Stranski-Krastanov mode of growth, while thin film growth was observed for T-SUB = 825-1050 degrees C. The growth rate decreased at higher T-SUB, whereas it increased sharply for T-P = 800-850 degrees C followed by a quasi-saturation for T-P = 800-1000 degrees C. The growth rate evolution in both experiments reveals the significant role of gallium suboxide formation and desorption at the precursor/film during b-Ga2O3 LPCVD. This study provides useful insights into the growth dynamics involved in LPCVD of b-Ga2O3.