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

摘要

We report on record low free carrier concentration values in metalorganic chemical vapor deposition (MOCVD) grown β-Gasub2/subOsub3/sub by using Nsub2/subO for oxidation. Contrary to the pure oxygen, the Nsub2/subO oxidant produced β-Gasub2/subOsub3/sub 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-Gasub2/subOsub3/sub thin films with N and H concentrations ranging as high as ～2 × 10sup19/sup cmsup?3/sup and ～7 × 10sup18/sup cmsup?3/sup, 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 cmsup2/sup/V s with the corresponding free carrier concentration of 2.4 × 10sup14/sup cmsup?3/sup. This is the lowest room temperature carrier concentration reported for MOCVD grown β-Gasub2/subOsub3/sub with excellent electron mobility. A thin β-Gasub2/subOsub3/sub buffer layer grown using Nsub2/subO 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 Nsub2/subO 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.