Photo-responsivity of a Si-based MIS photo-detector with multi-dielectric layers

We demonstrate the fabrication and characterizations of a white light blinded photo-detector based on a Si based metal insulator semiconductor (MIS) device structure with multi-layers of SiO₂/TiO₂ dielectric. Spectral responsivity peak at 850 nm with high discrimination in visible light had been achieved with 10 layers of SiO₂/TiO₂ dielectrics. Reflection spectral measurements and I-V characteristics were used to study the photo-detection performance of the fabricated MIS device with various layer numbers and thickness. We found that effective spectral discrimination of visible light can be achieved by this multi-dielectric layers with designed structure and materials selected. In addition, we have found the enhancement of the photo-current beyond IR range. A mechanism of carriers excitation in these multi-dielectric layers by mid-band gap impurity states at the interface between the Si substrate and the dielectric layer is discussed.