A low cost n-SiCN/p-PS/p-Si heterojunction for high temperature ultraviolet detecting applications

In this paper, we investigated the n-SiCN/p-PS/p-Si heterojunction for low cost and high temperature ultraviolet (UV) detecting applications. The crystalline SiCN film was deposited on p-(100) porous silicon (PS)/silicon substrate with rapid thermal chemical vapor deposition (RTCVD) system. The p-PS serves as a buffer layer with features of high resistivity and flexibility to suppress dark current of an optical sensing device at high temperature. As a result a high photocurrent to dark current ratio (PDCR) can be achieved. At room temperature, the measured PDCR of the n-SiCN/p-PS/p-Si heterojunction with and without irradiation of 254 nm UV light, under −5 V bias and 0.5 mW/cm2 light power is ∼98.3. Even up to 200 °C, the ratio is still high to ∼8.5. These results are better than that of the reported SiCN film or ZnO nanowires on Si substrate UV detectors without the p-PS buffer layer.