Enhanced Visible-NIR Dual-Band Performance of GaAs Nanowire Photodetectors Through Phase Manipulation

High-quality 1D nanowires (NWs) are widely used in photodetectors due to their exceptional optoelectronic properties. However, internal structural defects and surface states trap carriers, limiting device performance. In this study, low-defect-density GaAs NWs are synthesized using molecular beam epitaxy (MBE) combined with the droplet wetting method, effectively reducing non-radiative recombination due to defect states and enabling high-performance dual-band photodetectors for visible (VIS) to near-infrared (NIR) wavelengths. Compared to defect-rich GaAs NWs, the high-quality GaAs NW photodetector shows a 6.5-fold increase in responsivity and a 4.7-fold improvement in detectivity at a VIS wavelength of 532 nm, achieving values of 615.2 A W⁻¹ and 9.1 × 10¹² Jones. Similarly, the devices exhibit a 10.7-fold increase in responsivity and a 12.1-fold improvement in detectivity at a NIR wavelength of 808 nm. Furthermore, response time measurements highlight the influence of defects on photoelectric characteristics. Carrier transport mechanisms under varying defect densities are analyzed in detail through numerical simulations. These results emphasize the potential of high-quality NWs with exceptional photoelectric properties to drive advancements in next-generation nanoscale optoelectronic devices.