High-speed cu-doped zns/n-si heterojunction photodiode for enhanced uv detection

Abstract

Ultraviolet (UV) photodetectors are crucial for applications ranging from environmental monitoring to advanced optical systems. However, achieving both high sensitivity and fast response in the UV range remains challenging. We present a high-speed UV photodiode based on a Cu-doped ZnS thin film grown on n-Si by thermionic vacuum arc (TVA) deposition. Introducing Cu into ZnS significantly improved the film's crystallinity and induced p-type behavior in ZnS, forming a robust p-n heterojunction with the n-Si. The Cu-doped device exhibits enhanced optoelectronic performance, with a peak responsivity of approximately 149 mA/W (corresponding to an external quantum efficiency of similar to 49 %) under UV illumination, as well as rapid transient response characteristics (rise time similar to 6.6 mu s and fall time similar to 291 mu s). The-3 dB bandwidth reaches about 7 kHz, demonstrating significant highspeed performance. These performance metrics are competitive with the latest state-of-the-art UV photodetectors (see Table 5), highlighting the efficacy of Cu doping and TVA fabrication in advancing ZnS-based photodiodes. Overall, the ZnS:Cu/n-Si photodiode combines high sensitivity and speed, showing potential for future UV sensing technologies and integration into next-generation UV optoelectronic systems.