High-performance self-powered UV-Vis-NIR photodetectors based on horizontally aligned GaN microwire array/Si heterojunctions

Considering their reduced size and weight, low cost and portability, self-powered photodetectors that can be functioned independently of an external power supply are extremely important for developing future sensor networks and Internets of Things. Here, we present a self-powered photodetector with a broadband wavelength photoresponse from the ultraviolet to near-infrared region based on GaN microwire array/Si heterojunctions. Due to the highly efficient separation of photogenerated charge carriers, the photodetector shows ultrahigh EQE, responsivity and detectivity, reaching up to 71%, 4.7 x 10(2) mA W-1 and 9.5 x 10(12) Jones, respectively, at zero bias in the 320-850 nm range. A fast response is observed with rise/decay times as low as 2/2 ms. The LDR values are over 80 dB. The performance characteristics are competitive with commercially available biased photodetectors and other reported heterojunction self-powered broadband photodetectors in the literature. In addition, a binary photoresponse is observed under small bias voltages. The heterostructures are fabricated by directly heteroepitaxially growing GaN microwires on patterned Si, enabling large-area device applications, and stand out from low-dimensional semiconductor photodetection systems. The overall high performance coupled with large-scale production makes GaN microwire array/Si heterojunctions promising for practical self-powered broadband photodetectors.