Si/SnSe-Nanorod Heterojunction with Ultrafast Infrared Detection Enabled by Manipulating Photo-Induced Thermoelectric Behavior

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 x 10(10) cm Hz(1)(/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 mu s. 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.

Automated summary

In this study, Si/SnSe nanorod photothermal detectors were fabricated to achieve high-performance infrared response beyond the bandgap limitation. By manipulating the photoinduced thermoelectric behavior, a unique four-stage photoresponse and ultrafast infrared photothermal response were achieved.