Piezo-phototronic enhanced photoresponsivity based on single CdTe nanowire photodetector

The piezo-phototronic effect utilizes the piezo-polarization charge to modify the energy band diagram at the local interface/junction and manipulate the optoelectronic processes of charge carriers, which have provided a promising approach to improve the performance of photoelectric devices. In this paper, we report on the fabrication of single ultra-fine CdTe nanowire (NW) piezo-phototronic photodetectors (PDs). The structure and morphology of the as-synthesized CdTe NWs is characterized in detail. The result shows that the CdTe NWs have a single crystalline zinc blende structure, with its diameter narrowing to about 20 nm. The flexible Ag-CdTe NW-Ag lateral PDs are prepared on the polyethylene terephthalate substrate, showing a broadband photoresponse from ultraviolet to near infrared (NIR) (325-808 nm). By introducing the piezo-phototronic effect, strain-induced piezoelectric polarization charges effectively enhance the performances of the NIR PDs (808 nm) by 430% in photocurrent and 427% in photoresponsivity. The physical mechanism is carefully investigated by analyzing the energy band diagrams at the local metal–semiconductor interface under mechanical deformations. The ultra-fine structure with a larger piezoelectric coefficient is attributed to the enhancement of photoresponsivity. This investigation demonstrates an efficient prototype of the broad-wavelength piezo-phototronic PD based on the ultra-fine CdTe NWs, which provides an effective route to enhance the performance of optoelectronic devices.