Probing Charge Transport and Background Doping in Metal-Organic Chemical Vapor Deposition-Grown (010) β-Ga2O3

A new record-high room-temperature electron Hall mobility (mu(RT) = 194 cm(2) V-1 s(-1) at n approximate to 8 x 10(15) cm(-3)) for beta-Ga2O3 is demonstrated in the unintentionally doped thin film grown on (010) semi-insulating substrate via metal-organic chemical vapor deposition (MOCVD). A peak electron mobility of approximate to 9500 cm(2) V-1 s(-1) is achieved at 45 K. Further investigation on the transport properties indicates the existence of sheet charges near the epilayer/substrate interface. Si is identified as the primary contributor to the background carrier in both the epilayer and the interface, originating from both surface contamination and growth environment. The pregrowth hydrofluoric acid cleaning of the substrate leads to an obvious decrease in Si impurity both at the interface and in the epilayer. In addition, the effect of the MOCVD growth condition, particularly the chamber pressure, on the Si impurity incorporation is studied. A positive correlation between the background charge concentration and the MOCVD growth pressure is confirmed. It is noteworthy that in a beta-Ga2O3 film with very low bulk charge concentration, even a reduced sheet charge density plays an important role in the charge transport properties.