Study on the Transient Response Performance and Mechanism of Si/ZnO Heterojunction Photodetectors Controlled by Interface Electric Field Direction

Abstract Self‐powered photodetectors based on transient current response have excellent optoelectronic performance and environmental adaptability, indicating significant promise for sensors and imaging applications. However, the physical mechanism underlying the substantial disparities in transient current responsiveness among various heterojunction devices remains ambiguous, impeding their advancement and utilization. Here, p‐Si/n‐ZnO and n‐Si/n‐ZnO heterojunction devices are constructed, and their transient response characteristics under broad‐spectrum light excitation are studied. The n‐n heterojunction devices exhibit superior optoelectronic response characteristics, with a responsivity, linear dynamic range and linear factor of 637.7 mA W −1 , 124 dB, and 1.0, respectively. However, p‐n junctions exhibit poor optoelectronic response performance. Reducing the surface and interface states of ZnO can significantly improve the response performance of p‐n heterojunction devices but has little effect on n‐n heterojunction devices. The different directions of photogenerated carrier transport driven by the interface electric field in these two types of devices are the primary cause for their performance disparities. According to the devices’ photoelectric characteristics, they are suitable for rapid photodetection in intricate environments and preprocessing of images, respectively. This work will offer theoretical guidance for the design of high‐performance and multifunctional Si/ZnO heterojunction devices and promote their extensive application in optoelectronic sensing and high‐speed imaging fields.