Enhanced Broad Band Photodetection through Piezo‐Phototronic Effect in CdSe/ZnTe Core/Shell Nanowire Array

Abstract

The piezo‐phototronic effect is of immense importance for improving the performance of optoelectronic nanodevices. This is accomplished by tuning the charge carrier generation, separation, and transport under the influence of the inner piezopotential. In this paper, a broad band photodetector is demonstrated that is based on II‐VI binary CdSe/ZnTe core/shell nanowire arrays, in which photodetection is greatly enhanced by the piezo‐phototronic effect. The photodetector performance under UV (385 nm), blue (465 nm), and green (520 nm) illumination infers a saturation free response with an intensity variation near two orders of magnitude, where the peak photocurrent (125 μA) is two orders higher at 0.25 kilogram force (kgf) compared to no load (0.71 μA). The resulting (%) responsivity changed by four orders of magnitude. The significant increase in responsivity is believed to arise from: 1) the piezo‐phototronic effect induced by a change in the Schottky barrier height at the Ag–ZnTe junction, and in the type‐II band alignment at the CdSe–ZnTe interfaces, in conjugation with 2) a small lattice mismatch between the CdSe and ZnTe epitaxial layers, which lead to reduced charge carrier recombination. This work thus extends the piezo‐phototronic effect to a group II‐VI binary semiconductor heterostructure and demonstrates the importance of the epitaxial interface in a core/shell nanowire photodetector.

Heterojunctions Based on II-VI Compound Semiconductor One-Dimensional Nanostructures and Their Optoelectronic Applications

“…Luo et al constructed CdS-ZnTe core-shell nano-heterojunction photodetectors and measured their photoresponse under light illumination with a wavelength of 638 nm and light intensity of 2 mW cm -2 at 1 V (Figure 14) [25]. The fabricated core-shell nano-heterojunction photodetectors exhibited responsivity of 1.55 × 10 3 AW −1 , conductive gain of 3.3 × 10 3 , detectivity of 8.7 × 10 12 cm Hz 1/2 W −1 , which are much higher than the devices based on is greatly enhanced by the piezo-phototronic effect [34]. Jie et al fabricated Ge-CdS core-shell heterojunction nanowire photodetectors with excellent diode characteristics and a pronounced photoresponse under light illumination.…”

“…Both devices showed much higher performance than the photodetectors based on ZnO, ZnTe, and CdSe nanowires [67][68][69]. Hz 1/2 W −1 , which are much higher than the devices based on is greatly enhanced by the piezo-phototronic effect [34]. Jie et al fabricated Ge-CdS core-shell heterojunction nanowire photodetectors with excellent diode characteristics and a pronounced photoresponse under light illumination.…”

“…Furthermore, EDS line scan collected along the lateral Regarding the core-shell architecture, 3-D core-shell nanowire array structure provides additional advantages over single nanowire-based devices owing to their unique features, such as a large surface area, excellent multichannel charge transport, and enhanced light absorption through light trapping and scattering. Zhou et al fabricated a type of CdSe/ZnTe core-shell nanowire array for broad spectral detecting [34]. They first grew vertically aligned CdSe nanowire array on muscovite mica substrate by CVD method.…”

Ferroelectric and Piezoelectric Effects on the Optical Process in Advanced Materials and Devices

“…The combination of the expansion and shift of the depletion region as well as the band profile bending at the vicinity of p–n junction contributes to the optimal performances of photodetectors. With a similar mechanism, photodetectors made from CdSe/ZnTe core–shell structure also realize an improved photosensitivity …”

Progress in piezo-phototronic effect enhanced photodetectors

“…[127][128][129][130][131] Type-II heterostructures can extend the photoresponse spectral range to the longer wavelength which is dominated by the lower band gap component. Both the ZnO/ZnS and CdSe/ZnTe core-shell nanowires which have type II alignment exhibit an efficient broad band UV/visible photoresponse.…”