Probing the photoresponse of individual Nb₂O₅nanowires with global and localized laser beam irradiation

Abstract

Photoresponse of isolated Nb(2)O(5) nanowires (NW) padded with platinum (Pt) at both ends were studied with global irradiation by a laser beam and localized irradiation using a focused laser beam. Global laser irradiation on individual NW in ambient and vacuum conditions revealed photocurrent contributions with different time characteristics (rapid and slowly varying components) arising from defect level excitations, thermal heating effect, surface states and NW-Pt contacts. With a spot size of < 1 µm, localized irradiation highlighted the fact that the measured photocurrent in this single NW device (with and without applied bias) depended sensitively on the photoresponse at the NW-Pt contacts. At applied bias, unidirectional photocurrent was observed and higher photocurrent was achieved with localized laser irradiation at reverse-biased NW-Pt contacts. At zero bias, the opposite polarity of photocurrents was detected when the two NW-Pt contacts were subjected to focused laser beam irradiation. A reduced Schottky barrier/width resulting from an increase in charge carriers and thermoelectric effects arising from the localized thermal heating due to focused laser beam irradiation were proposed as the mechanisms dictating the photocurrent at the NW-Pt interface. Comparison of photocurrents generated upon global and localized laser irradiation showed that the main contribution to the photocurrent was largely due to the photoresponse of the NW-Pt contacts.

Strong Photocurrent from Two-Dimensional Excitons in Solution-Processed Stacked Perovskite Semiconductor Sheets

“…Despite the relatively low diffusion rate of the holes, the photocurrents at the positive terminal are always higher than those at the negative terminal ( Figure 5 d), which occurs when the semiconducting channel is of the p-type. 47 Therefore, these scanning photocurrent microscopy measurements imply that this CHPI 2D perovskite is a p-type semiconductor. Mitzi et al used extensive varieties of related 2D IO perovskites (tin- and lead-based) in transistors and also found them to be in the p-type, 11 , 12 , 50 , 51 as indeed is also the parent PbI 2 .…”

A Comprehensive Review of Semiconductor Ultraviolet Photodetectors: From Thin Film to One-Dimensional Nanostructures

“…The photodetector showed a high UV-A-light sensitivity, high external quantum efficiency of 6070%, and excellent photocurrent stability of more than 2,500 s. Photoresponse of isolated Nb 2 O 5 nanowires were also studied by using global and localized focused laser beam irradiation by Tamang et al . [122]. A fast and prominent photoresponse was found towards visible and infrared laser irradiation.…”

Electrochemical Energy Storage Applications of CVD Grown Niobium Oxide Thin Films

“…Recent reports include the integration of Nb2O5 in electrode materials in supercapacitor applications, which has resulted in excellent performances ascribed to the pseudocapacitance effect involved. [13][14][15] However, the niobium-oxygen system is particularly complex, as narrow deviations from the exact stoichiometry in Nb2O5 strongly affect the physical properties of the material. For instance, a small oxygen deficiency leads to the transition from insulating to n-type semiconducting behavior 9 .…”