Improved ultraviolet/visible rejection ratio using MgZnO/SiO2/n-Si heterojunction photodetectors

We report on the fabrication and characterization of MgZnO/SiO2/n-Si structured photodetectors, for the visible–blind monitoring. The current–voltage curve of the heterojunction shows obvious rectifying behaviors. In the visible range, the photocurrent decreased rapidly. In additionally, the ultraviolet/visible rejection ratio (R340 nm/R500 nm) was about four orders of magnitude at reverse bias, indicating a high degree of visible blindness. The key role of the insulating SiO2 layer will be discussed in terms of the band diagrams of the heterojunctions.