Low pressure chemical vapor deposition of β-Ga2O3 thin films: Dependence on growth parameters

Low pressure chemical vapor deposition (LPCVD) has been used to produce high quality beta-Ga2O3 materials with controllable n-type doping. In this work, we focus on the studies of key LPCVD growth parameters for beta-Ga2O3 thin films, including oxygen/carrier gas flow rates, growth temperature, pressure, and the substrate to Ga crucible distance. These growth parameters play important roles during the LPCVD beta-Ga2O3 growth and determine the thin film growth rate, n-type dopant incorporation, and electron mobilities. The dependence of the growth parameters on LPCVD of beta-Ga2O3 was carried out on both conventional c-plane sapphire and 6 degree off-axis (toward < 11-20 > direction) sapphire substrates. To better understand the precursor transport and gas phase reaction process during the LPCVD growth, a numerical model for evaluating the growth rate was developed by using a finite element method and taking into account the gas flow rate, chamber pressure, and chamber geometry. The results from this work can provide guidance for the optimization of the LPCVD growth of beta-Ga2O3 with targeted growth rate, surface morphology, doping concentration, and mobility. In addition, beta-Ga2O3 grown on off-axis c-sapphire substrates features with faster growth rates with higher electron mobilities within a wide growth window. (C) 2018 Author(s).