Epitaxial structure and electronic property of β-Ga2O3 films grown on MgO (100) substrates by pulsed-laser deposition

We investigated heteroepitaxial growth of Si-doped Ga2O3 films on MgO (100) substrates by pulsed-laser deposition as a function of growth temperature (T-g) to find a strong correlation between the structural and electronic properties. The films were found to contain cubic gamma-phase and monoclinic beta-phase, the latter of which indicated rotational twin domains when grown at higher T-g. The formation of the metastable gamma-phase and twin-domain structure in the stable beta-phase are discussed in terms of the in-plane epitaxial relationships with a square MgO lattice, while crystallinity of the beta-phase degraded monotonically with decreasing T-g. The room-temperature conductivity indicated a maximum at the middle of T-g, where the beta-Ga2O3 layer was relatively highly crystalline and free from the twin-domain structure. Moreover, both crystallinity and conductivity of beta-Ga2O3 films on the MgO substrates were found superior to those on alpha-Al2O3 (0001) substrates. A ratio of the conductivity, attained to the highest quantity on each substrate, was almost three orders of magnitude. Published by AIP Publishing.