Sub-band response of PZT photodetector controlled by back-gate voltage

Abstract

Sub-band energy levels induced photo-conduction mechanisms play a significant role in the extension of the response spectra within a photodetector. Herein, we reported a PbZr0.32Ti0.68O3 (PZT) based photodetector for sub-band photoresponse excited by a 450 nm blue laser. Sub-band induced by the defects acts as the intermediate state for the intra-band transition excited by the blue laser, in which the photon energy is smaller than the bandgap of the PZT thin film. Within both gate-controlled and blue laser driven operations, the source to drain current (I sd) can be precisely modulated. The photocurrent and response speeds of the device are also studied under air and vacuum conditions, which shows negligible fluctuations under different atmospheres and excludes the negative influence from the defect-related surface states. The proposed device configuration provides a simple and cost-effective visible light driven photodetector, which may give rise to an interesting route towards optoelectronic devices based on ferroelectric material.