Low 10(14) cm(-3) free carrier concentration in epitaxial beta-Ga2O3 grown by MOCVD

We report on record low free carrier concentration values in metalorganic chemical vapor deposition (MOCVD) grown beta-Ga2O3 by using N2O for oxidation. Contrary to the pure oxygen, the N2O oxidant produced beta-Ga2O3 thin films co-doped with nitrogen and hydrogen, but the incorporation efficiency of both impurities is strongly dependent on key MOCVD growth parameters. An array of growth conditions resulted in beta-Ga2O3 thin films with N and H concentrations ranging as high as similar to 2 x 10(19) cm(-3) and similar to 7 x 10(18) cm(-3), respectively, to films with no SIMS detectable N and H was identified. Films grown without detectable N and H concentrations showed a room temperature electron mobility of 153 cm(2)/V s with the corresponding free carrier concentration of 2.4 x 10(14) cm(-3). This is the lowest room temperature carrier concentration reported for MOCVD grown beta-Ga2O3 with excellent electron mobility. A thin beta-Ga2O3 buffer layer grown using N2O reduced the net background concentration in an oxygen grown film and is attributed to the compensation of Si at the film/substrate interface by N, which acts as a deep acceptor. The results show that the use of the N2O oxidant can lead to low background concentration and high electron mobility, which paves the road for the demonstration of high-performance power electronic devices with high breakdown voltages and low on-resistances. (c) 2020 Author(s).