Metasurface Enabled Photothermoelectric Photoresponse of Semimetal Cd<sub>3</sub>As<sub>2</sub> for Broadband Photodetection.

Xue, Zhaohang; Fan, Zipu; Liao, Xin; Li, Yaolong; Qin, Yulu; Zhang, Guanyu; Song, Xiaoming; Liao, Zhi-Min et al. · Nano Lett · 2022

basic_science · Level V

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Abstract

The artificial engineering of photoresponse is crucial for optoelectronic applications, especially for photodetectors. Here, we designed and fabricated a metasurface on a semimetallic Cd<sub>3</sub>As<sub>2</sub> nanoplate to improve its thermoelectric photoresponse. The metasurface can enhance light absorption, resulting in a temperature gradient. This temperature gradient can contribute to thermoelectric photoresponse through the photothermoelectric effect. Furthermore, power-dependent measurements showed a linearly dependent photoresponse of the Cd<sub>3</sub>As<sub>2</sub> metasurface device, indicating a second-order photocurrent response. Wavelength-dependent measurements showed that the metasurface can efficiently separate photoexcited carriers in the broadband range of 488 nm to 4 μm. The photoresponse near the metasurface boundaries exhibits a responsivity of ∼1 mA/W, which is higher than that near the electrode junctions. Moreover, the designed metasurface device provided an anisotropic polarization-dependent photoresponse rather than the isotropic photoresponse of the original Cd<sub>3</sub>As<sub>2</sub> device. This study demonstrates that metasurfaces have excellent potential for artificial controllable photothermoelectric photoresponse of various semimetallic materials.