Bandgap-independent photoconductive detection in two-dimensional Sb2Te3

Abstract

Broadening the spectral range of photodetectors is vital for photodetection. However, current photoelectric detectors are selective to wavelength, which depends on bandgap, and thermal detectors respond slowly at room temperature. It is challenging to achieve photoconductivity independent of the semiconductor bandgap, which is needed to broaden the spectral range of photodetectors. Here, we use 2D semiconductor Sb2Te3 to develop a photodetector with metal-semiconductor-metal structure for multiband response, covering visible, infrared, terahertz and millimeter wavelengths at room temperature. This is achieved by the synergy of the photoconductivity of photo-excited electron-hole pairs above the bandgap, and an electromagnetic-induced well effect below the bandgap. The photodetector achieves a responsivity of 0.6 A W−1 at 1550 nm, 515 A W−1 at 0.340 THz with a bias of 0.2 V, respectively. The response time is 900 ns, which is short compared to the reported detectors based on 2D materials. In addition, it also exhibits a high polarization extinction ratio of 90. These results suggest that our strategy achieves a photoconductivity independent of the semiconductor bandgap to broaden the spectral range of photodetectors, and could be a strong candidate for multiband photodetection systems.