Photoconductive Characteristics of Single-Crystal CdS Nanoribbons

Abstract

The photoconductive characteristics of CdS single nanoribbons were investigated. The device characteristics, including spectral response, light intensity response, and time response, were studied systematically. It is found that CdS nanoribbon has the response speed substantively faster than those ever reported for conventional film and bulk CdS materials and the size of nanoribbons has a significant influence on the response speed with smaller CdS nanoribbons showing higher response speed. The high photosensitivity and high photoresponse speed are attributable to the large surface-to-volume ratio and high single-crystal quality of CdS nanoribbons and the reduction of recombination barrier in nanostructures. Measurements in a different atmosphere demonstrate that the absorption of ambient gas (mainly oxygen) can significantly change the photosensitivity of CdS nanoribbons through trapping electrons from the nanoribbons.

Channel length specific broadspectral photosensitivity of robust chemically grown CdS photodetector

“…Note that increase in wavelength means decrease in energy to shift charge carriers from valence band to conduction band and decrease in rise time could be observed. Additionally we have performed the time dependent photocurrent measurements with on off cycles of a fixed wavelength and observed no time dependent significant change on the response 26 Other reports of CdS nanoribbons showed rise and decay time (551 µs and 1.093 ms), 27 (1 sec and 3sec) 28 and 31 ms decay time for CdS belt synthesized by the vapour phase transportation method. 29 The rise and decay time for CdS nanowire (15 ms) 30 and the aligned networks (0.8, 240 ms) have been also reported earlier.…”

“…29 The rise and decay time for CdS nanowire (15 ms) 30 and the aligned networks (0.8, 240 ms) have been also reported earlier. 10 It is important to note that, no distinct photoresponse was observed for the pure CdS nanobelt at higher wavelengths (> 532 nm) 26 but distinct photorespose was noticed for energy smaller than the bad gap when the CdS nanowire was doped with tin. 31 We cannot compare rise and decay with nanostructures or crystalline quality materials but CLs investigations may be studied further or improved for better quality films.…”

Large-scale, heterogeneous integration of nanowire arrays for image sensor circuitry

“…Each photoresponse cycle consists of three transient regimes-a sharp rise ( Ϸ0.7 sec), steady state, and sharp decay ( Ϸ0.7 sec). We note that our time constants are larger than the best reported values for nanowires in the literature (21,33). We attribute this to (i) the quality of our nanowires, which can be readily improved in the future through growth optimization, and (ii) the measurement setup.…”

“…CdSe-and CdS-based nanomaterials such as quantum dots and NWs have been extensively explored in the past, and their superb optical and opto-electrical properties have been reported in detail by various groups (31)(32)(33). Notably, NWs (for instance, in the case of ZnO NWs) have been shown to be ideal materials for photodetection with significantly higher sensitivities than their bulk counterparts, arising from their high surface area-to-volume ratio that results in high density of surface states (21,33). The surface states trap the photogenerated holes and, therefore, effectively increase the electron carrier lifetime that results in the enhancement of the photocurrent (21).…”

Plasmonic hollow gold nanoparticles induced high-performance Bi2S3 nanoribbon photodetector

“…Figure 6 plots the photocurrents as a function of light intensity, from which one can find that the photocurrent increases almost linearly with increasing intensity. Carful fitting of both values finds that their relationship could be described by a power law [39]: I =AP θ , where I, A, P and θ represent the photocurrent, the constant depending on the wavelength, the light power intensity and the exponent determining the response to light intensity, respectively. By fitting the curves, the θ for HGN@Bi 2 S 3 NR is estimated to 0.96, slightly larger than that of pure Bi 2 S 3 NR (0.91).…”