Impact of c- and m- sapphire plane orientations on the structural and electrical properties of β-Ga2O3 thin films grown by metal-organic chemical vapor deposition

This work presents a comprehensive investigation into the structural and electrical properties of Ga2O3 thin films grown via metal-organic chemical vapor deposition on both c- and m-plane sapphire substrates. Structural characterization revealed the beta-Ga2O3 phase formation in both substrate orientations, with strong epitaxial ((2) over bar 01) preferential growth on c-plane substrates and polycrystalline films on m-plane substrates. Results show that Ga2O3/m-sapphire exhibits the lower electrical resistivity than its counterpart grown on c-sapphire. Activation energies of acceptor levels were estimated at similar to 1.4 eV and similar to 0.7 eV, for Ga2O3 films grown on c- and m-plane, respectively. This result shows that growing Ga2O3 on m-plane sapphire is beneficial to reach a weakly compensated sample. Cathodoluminescence analysis suggests that the additional low activation energy of similar to 0.18 eV observed in Ga2O3 grown with the highest oxygen flow on m-plane sapphire can be associated to thermally-induced migration of self-trapped hole states.