Dramatically enhanced carrier mobility and Curie temperature in n-p codoped ZnO by proximity effect.

• The proximity effect of graphene effectively improves the mobility and Curie temperature of the composite system. • There is a significant charge transfer at the interface between graphene and (V, N)ZnO. • The (V, N) doping pair on the surface of ZnO induces spin polarization of the graphene. Oxide-based diluted magnetic semiconductors usually exhibit above room-temperature ferromagnetism, but low carrier mobility limits their applications in novel spintronics. In this study, using first-principles calculation, the mobility, electronic and magnetic properties of V-N codoped ZnO((V, N)ZnO) system and its composite system (V, N)ZnO/graphene are studied. Compared with (V, N)ZnO, our results show that the electron mobility of the composite system is obviously increased by about three times (from 500 cm2 V−1 s−1 to 1500 cm2 V−1 s−1). In addition, we find that the ferromagnetism of the composite system is largely enhanced than that of the only V-N codoped ZnO. The Curie temperature of the composite system is estimated to be about 630 K based on the mean-field approximation theory, which is nearly twice as high as the (V, N)ZnO(321 K). This study provides effective theoretical guidance for improving carrier mobility and Curie temperature of oxide based dilute magnetic semiconductors. [ABSTRACT FROM AUTHOR]