Si/SnSe-Nanorod Heterojunction with Ultrafast Infrared Detection Enabled by Manipulating Photo-Induced Thermoelectric Behavior
Yingming Liu, Yunjie Liu, Yupeng Wu, Shirong Zhao, Fuhai Guo, Siqi Li, Weizhuo Yu, Guanchu Liu, Jingyi Hao, Zegao Wang, Keyou Yan, Lanzhong Hao
Abstract
Photothermal detectors have attracted tremendous research interest in uncooled infrared imaging technology but with a relatively slow response. Here, Si/SnSe-nanorod (Si/SnSe-NR) heterojunctions are fabricated as a photothermal detector to realize high-performance infrared response beyond the bandgap limitation. Vertically standing SnSe-NR arrays are deposited on Si by a sputtering method. Through manipulating the photoinduced thermoelectric (PTE) behavior along the c-axis, the Si/SnSe-NRs heterojunction exhibits a unique four-stage photoresponse with a high photoresponsivity of 106.3 V W–1 and high optical detectivity of 1.9 × 1010 cm Hz1/2 W–1 under 1342 nm illumination. Importantly, an ultrafast infrared photothermal response is achieved with the rise/fall time of 11.3/258.7 μs. Moreover, the coupling effect between the PTE behavior and external thermal excitation enables an improved response by 288.4%. The work not only offers a new strategy to develop high-speed photothermal detectors but also performs a deep understanding of the PTE behavior in a heterojunction system.