Dual-color ultraviolet photodetector based on mixed-phase-MgZnO/i-MgO/p-Si double heterojunction

We report a dual-color ultraviolet (UV) photodetector based on mixed-phase-MgZnO/i-MgO/p-Si double heterojunction. The device exhibits distinct dominant responses at solar blind (250 nm) and visible blind (around 330 nm) UV regions under different reverse biases. By using the energy band diagram of the structure, it is found that the bias-tunable two-color detection is originated from different valence band offset between cubic MgZnO/MgO and hexagonal MgZnO/MgO. Meanwhile, due to the large conduction band offset at the Si/MgO interface, the visible-light photoresponse from Si substrate is suppressed. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4746772]