Research progress of silicon nanowires array photodetectors

Abstract

As one of the most important semiconductor materials, silicon (Si) is widely used in optoelectronic devices such as solar cells and photodetectors. Owing to the difference in refractive index between silicon and air, a large amount of incident light is reflected back into the air from the silicon surface. In order to suppress the loss caused by this reflection, a variety of silicon nanostructures with strong trapping effect have been developed. Most of the dry-etching schemes encounter the problems of high cost and complex preparation, while the silicon nanowires array prepared by the wet-etching schemes has the problems of low controllability of some parameters such as the spacing between two adjacent nanowires, and the small effective area of heterojunction. The method of using polystyrene microsphere as the mask can integrate the advantages of dry-etching method and wet-etching method, and it is easy to obtain periodic silicon nanowires (pillars) array. In this paper, first, we summarize the properties and preparation methods for silicon nanowires structure, the strategies to effectively improve the performance of silicon nanowires (pillars) array photodetectors, Then we analyze the existing problems. Further, the latest developments of silicon nanowires (pillars) array photodetector are discussed, and the structure, morphology of photosensitive layer and methods to improve the performance parameters of silicon nanowires (pillars) array photodetector are analyzed. Among them, we focus on the ultraviolet light sensitive silicon based photodetector and its method to show tunable and selective resonance absorption through leaky mode resonance, the silicon nanowires array photodetector modified with metal nanoparticles and the method of improving performance through surface plasmon effect, and plasmon hot electrons. Heterojunction photodetectors composed of various low-dimensional materials and silicon nanowires (pillars) array, and methods to improve the collection efficiency of photogenerated charge carriers through the “core/shell” structure, methods to expand the detection band range of silicon-based photodetectors by integrating down-conversion light-emitting materials and silicon nanowires (pillars) array, flexible silicon nanowires array photodetectors and their various preparation methods, are all introduced. Then, the main problems that a large number of defect states will be generated on the silicon nanostructure surface in the MACE process are briefly introduced, and several possible solutions for defect passivation are also presented. Finally, the future development for silicon nanowires (pillars) array photodetectors is prospected.