Charge Transfer at the Interfaces of PolycrystallineZnO/Zn_(1-x)Mg_xO/ZnO Heterostructures

摘要

Charge transfer at the interfaces of polycrystalline ZnO/Zn_(1-x)Mg_xO(ZnMgO)/ZnO heterostruc-tures, which were grown on glass substrates by using ultrasonic spray pyrolysis, were investigatedby measuring the electrical and the optical properties of the heterostructures. Spectral blue shiftsof optical band gap were observed for ZnO/ZnMgO/ZnO heterostructures and were analyzed interms of Burstein-Moss and band-gap-renormalization effects to estimate the amount of chargetransfer. Compared to a single-layer Al-doped ZnO (ZnO:Al) films, the electrical properties of theZnO:Al/ZnMgO/ZnO:Al heterostructure were found to be enhanced with increasing electron mo-bility by a factor of 1.6. Even in these polycrystalline heterostructures, the conduction band offsetbetween ZnMgO and ZnO:Al can cause electron transfer at the interface and decrease the energybarrier at the grain boundaries, resulting in an enhanced of mobility.