Giant room-temperature terahertz photothermoelectric response mediated by hot carriers at the metal-semimetal interfaces
Miao Cai, Jinhua Zhang, Yuanbo Chen, Liang Hong, Jingjing Fu, Xiantao Zheng, Yifan Yao, Shichen Zhang, Yinjun Liu, Boyu Dong, Shu Chen, Ping Li, Guanjun You, Junwen Zhang, Xuguang Guo, Yiming Zhu, Songlin Zhuang
Abstract
The hot-carrier photothermoelectric (PTE) effect in two-dimensional materials can be used to develop room-temperature, fast, and sensitive detectors for microwave, terahertz, and far-infrared radiations. Here, we present a van der Waals semimetal PtSe 2 terahertz detector and find a giant terahertz PTE response mediated by hot carriers at the metal-PtSe 2 interfaces. The detector demonstrates an excellent zero-bias responsivity of 0.62 ampere per watt (A/W), a low-noise equivalent power of 19.6 picowatt per square root of hertz (pW/Hz 1/2 ), and a fast response time of 4.5 nanosecond (ns) at 0.1 terahertz (THz). The metal doping effect and asymmetric terahertz heating play vital roles in the hot-carrier PTE response at the metal-semimetal interfaces. Moreover, scanning photocurrent mapping shows that the short-wave zero-bias photoresponse is closely localized to the metal-semimetal interfaces, further revealing the metal doping effect. The bias-dependent photocurrent indicates that the short-wave photoresponse still originates from the PTE effect and the photovoltaic response is negligible. Our results provide important guidance for developing high performance semimetal detectors.