Investigation of photocurrent transient variation in Au nanoparticles-decorated IGZO phototransistor

Abstract

Due to the surface plasmon induced hot electrons effect, noble metallic nanostructures as photosensitizer have been widely applied for extending the photoresponse spectra of wideband semiconductors to visible range. However, most of those researches only focused on how to extend the photoresponse spectra and to improve the hot electrons injection efficiency, few investigations about the effect of hot electrons injection process on the photocurrent transient variation. In this paper, we firstly extended the photoresponse spectra of IGZO phototransistors to visible range by decorating the channels with the Au nanoparticles (AuNPs), and then specifically investigated the influence of plasmon induced hot electrons injection process on the photocurrent by observing the photocurrent transient curve of AuNPs decorated IGZO phototransistors under different illumination conditions (405 nm, 532 nm, 658 nm). It was found that AuNPs decorated IGZO phototransistors show an overshoot peak at the rising edge (falling edge) of the photocurrent curve under 658 nm illumination (dark), while the bare IGZO phototransistors don't show this phenomenon. We proposed a dynamic transportation model of hot electrons to explain the possible reason and also found that the generation and injection efficiency of hot electrons are strongly dependent on the magnitude and location of the electric field enhancement. These findings will have a great significance for understanding the mechanism of plasmon induced hot electrons transfer process at the metallic/semiconductor interface and designing novel hot electrons based optoelectronic devices.