Low 1014  cm−3 free carrier concentration in epitaxial β-Ga2O3 grown by MOCVD

Abstract

We report on record low free carrier concentration values in metalorganic chemical vapor deposition (MOCVD) grown β-Ga2O3 by using N2O for oxidation. Contrary to the pure oxygen, the N2O oxidant produced β-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 β-Ga2O3 thin films with N and H concentrations ranging as high as ∼2 × 1019 cm−3 and ∼7 × 1018 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 cm2/V s with the corresponding free carrier concentration of 2.4 × 1014 cm−3. This is the lowest room temperature carrier concentration reported for MOCVD grown β-Ga2O3 with excellent electron mobility. A thin β-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.