Band alignment and interfacial structure of ZnO/Si heterojunction with Al2O3 and HfO2 as interlayers

Energy band alignment of ZnO/Si heterojunction with thin interlayers Al2O3 and HfO2 grown by atomic layer deposition has been studied using x-ray photoelectron spectroscopy. The valence band offsets of ZnO/Al2O3 and ZnO/HfO2 heterojunctions have been determined to be 0.43 and 0.22 eV, respectively. Accordingly, the band alignment ZnO/Si heterojunction is then modified to be 0.34 and 0.50 eV through inserting a thin Al2O3 and HfO2 layer, respectively. The feasibility to tune the band structure of ZnO/Si heterojunction by selecting a proper interlayer shows great advantage in improving the performance of the ZnO-based optoelectronic devices