Charge Transfer at the Interfaces of Polycrystaline ZnO/Zn1-xMgxO/ZnO Heterostructures

Charge transfer at the interfaces of polycrystalline ZnO/Zn1-xMgxO(ZnMgO)/ZnO heterostructures, which were grown on glass substrates by using ultrasonic spray pyrolysis, were investigated by measuring the electrical and the optical properties of the heterostructures. Spectral blue shifts of optical band gap were observed for ZnO/ZnMgO/ZnO heterostructures and were analyzed in terms of Burstein-Moss and band-gap-renormalization effects to estimate the amount of charge transfer. Compared to a single-layer Al-doped ZnO (ZnO:Al) films, the electrical properties of the ZnO: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 offset between ZnMgO and ZnO:Al can cause electron transfer at the interface and decrease the energy barrier at the grain boundaries, resulting in an enhanced of mobility. KCI Citation Count: 7