High-performance and broadband photodetection of bicrystalline (GaN)_1-x(ZnO)_x solid solution nanowires via crystal defect engineering

Crystal defect engineering is widely used as an effective approach to regulate the optical and optoelectronic properties of semiconductor nanostructures. However, photogenerated electron-hole pair recombination centers caused by structural defects usually lead to the reduction of optoelectronic performance. In this work, a high-performance photodetector based on (GaN)_1-x(ZnO)_x solid solution nanowire with bicrystal structure is fabricated and it shows excellent photoresponse to ultraviolet and visible light. The highest responsivity of the photodetector is as high as 60, 86 and 43 A/W under the irradiation of 365 nm, 532 nm and 650 nm, respectively. The corresponding response time is as fast as 170, 320 and 160 ms. Such wide spectral responses can be attributed to various intermediate energy levels induced by the introduction of various structural defects and dopants in the solid solution nanowire. Moreover, the peculiar bicrystal boundary along the axial direction of the nanowire provides two parallel and fast transmission channels for photo-generated carriers, reducing the recombination of photo-generated carriers. Our findings provide a valued example using crystal defect engineering to broaden the photoresponse range and improve the photodetector performance and thus can be extended to other material systems for various optoelectronic applications.