Hysteresis Behavior and Photoresponse Enhancement in Au Nanoparticle-Decorated Ge Photodetectors

Au nanoparticles (NPs) were drop-casted onto germanium (Ge) devices to investigate the influence of Au NPs on the electronic transport and photodetection properties of Ge metal-semiconductor-metal photodetectors. A significant hysteresis behavior was observed in the current-voltage curves of the Au NP-decorated Ge photodetector, which was ascribed to the energy band bending below the Au NPs and the electrostatic effect of image charges in the Au NPs. More interestingly, at the optical communication wavelength of 1.55 mu m, the introduction of Au NPs effectively improved the responsivity of the device from0.18 to 0.92A/W. Rather than the localized surface plasmon resonance effect, the increase of responsivity in the Au NP-decorated Ge photodetector was caused by a type-II liked energy band alignment, which enhanced the spatial electron-holeseparation effect. These results provide inspiration for the development of novel optoelectronic devices.

Automated summary

Au nanoparticles were deposited on germanium devices to study their impact on the electronic transport and photodetection properties of Ge metal-semiconductor-metal photodetectors. The introduction of Au NPs led to significant hysteresis behavior and improved responsivity at the optical communication wavelength of 1.55 μm. This increase in responsivity was attributed to a type-II liked energy band alignment, enhancing the spatial electron-hole separation effect. These findings offer inspiration for the development of innovative optoelectronic devices.