Selectively Modulated Photoresponse in Type-I Heterojunction for Ultrasensitive Self-Powered Photodetectors

Photodetectors based on two-dimensional (2D) van der Waals heterostructures (vdWHs) have demonstrated great potential in modern nanotechnologies across a wide range of applications. However, due to the severe interface recombination of the photogenerated electron-hole pairs and various absorption edges of constituent layers, they would suffer from low carrier collection efficiency, and the spectral response range of each constituent layer is indistinguishable. Herein, tellurium (Te) nanoflakes with broadband photoresponse are synthesized to construct type-I InSe/Te vdWHs photodetector, which exhibits an ultralow reverse dark current of 3 x 10(-14) A and an ultrahigh current rectification ratio of 10(8). Moreover, considerable photovoltaic effect of the heterostructure device is observed under illumination, attaining a light on/off ratio of up to 10(5), a high specific detectivity of 1.77 x 10(11) Jones, and a fast response time of 320 mu s. Based on type-I band alignment, the Te layer can collect the photogenerated holes from the InSe layer to suppress the recombination of photogenerated carriers. More importantly, the spectral response of the InSe/Te heterostructure photodetector can be selectively modulated by the InSe layer. This work demonstrates that band alignment engineering of 2D vdWHs holds great potential for developing high-performance self-powered photodetectors.

Automated summary

This study presents the synthesis of tellurium nanoflakes with broadband photoresponse to construct a type-I InSe/Te van der Waals heterostructure photodetector. The detector exhibits ultralow dark current, ultrahigh current rectification ratio, considerable photovoltaic effect, and fast response time. Band alignment engineering of the heterostructure enables the development of high-performance self-powered photodetectors.