Mg acceptor doping in MOCVD (010) <b> <i>β</i> </b>-Ga2O3

Abstract

In this Letter, in situ Mg doping in β-Ga2O3 was demonstrated via metalorganic chemical vapor deposition (MOCVD) epitaxy. The electrical insulating property of the Mg acceptors in β-Ga2O3 was found to be intrinsically activated in the as-grown Mg-doped β-Ga2O3 thin films. Growth conditions for MOCVD β-Ga2O3 were further explored and optimized at a lower growth temperature regime, leading to a better confinement of the Mg-doping profile. Detailed analysis of Mg diffusion characteristics revealed a diffusion barrier energy Ebarrier ∼ 0.9 eV for Mg in MOCVD β-Ga2O3, which is likely related to an interstitial-assisted process. Surface morphologies and electron transport were characterized on samples grown with different growth temperatures and Mg doping levels. The MOCVD growth method demonstrated its feasibility to grow semi-insulating Mg-doped β-Ga2O3 epilayers with controllable Mg incorporation while maintaining good material quality and smooth surface morphology. From capacitance-voltage charge profiling, it is verified that the Mg-doped buffer layer grown at the substrate-epilayer interface could effectively compensate the charge accumulation at the interface. The in situ acceptor doping of Mg in MOCVD β-Ga2O3 will provide versatility for designing β-Ga2O3 power devices.