Polar-surface-driven growth of ZnS microsprings with novel optoelectronic properties

Abstract

Small perturbations during the growth kinetics of low-dimensional semiconductor structures may lead to novel features, which may provide an ideal system for understanding the fundamental physics of optical phenomena in optoelectronics devices. In this study, we report deformation-free single-crystal zinc sulfide (ZnS) microsprings produced by a polar-surface-driven growth process, and we thoroughly investigate the electrical characteristics of individual ZnS microsprings under electron beam irradiation and their initial applications in ultraviolet (UV) light sensors and waveguides. The microsprings produced are formed by a block-by-block stacking process following a hexagonal screw model that does not introduce distortion into the crystal lattices. The first photodetectors designed based on a single ZnS microspring exhibit a high spectral selectivity combined with a high photosensitivity and a fast response time (o0.3 s) under 320-nm illumination, which make ZnS microsprings particularly valuable as UV-light sensors. Concurrently, excellent waveguide performance along the fiber of a single ZnS microspring (for example,~0.13 dB μm − 1 at 450 nm, and~0.17 dB μm − 1 at 520 nm) is demonstrated for the first time. The high crystal quality, the fast response to UV light and the low propagation loss exhibited by ZnS microsprings indicate that they have important potential applications in nano-optoelectronic systems. NPG Asia Materials (2015) 7, e213; doi:10.1038/am.2015.100; published online 4 September 2015 INTRODUCTIONOne-dimensional semiconductor structures provide new opportunities to exploit the chemical and physical properties of materials at the micro-and nano-scales, making them promising candidates for future optoelectronic devices that take advantage of the well-controlled size, morphology and geometries of these materials. 1,2 The most recent studies have shown that bent nanowires or nanobelts can exhibit novel optical and electrical properties compared with their unbent counterparts, thus appreciably widening their potential applications in optoelectronic systems because optoelectronic characteristics in lowdimensional materials are particularly sensitive to crystallinity and electronic structures. 3 For example, in the photoluminescence spectra of bending wurtzite micro/nanowires, a red shift of the near-band energy induced by deformation has been shown to have a linear relation between the peak shift and the strain gradient. 4 Because the peaks of the photoluminescence spectra are near the band gap of these materials, such a linear correlation between the band gap and strain gradient could provide an alternative method in optoelectronics, such as enhanced photodetectors. 5 Conversely, from both scientific and practical viewpoints, one-dimensional structures are ideal materials to measure the optical gains of miniaturized lasers and light amplification due to their strong ability to confine electrons, holes and photons.

Highly Responsive Ultraviolet Sensor Based on ZnS Quantum Dot Solid with Enhanced Photocurrent

“…Figure 1(a,b) shows the UV-Vis absorption and PL emission spectra of ZnS samples prepared at different reaction time intervals. The optical UV absorption edge of the ZnS 6 hrs sample is observed around at 310 nm with a significant blue shift compared to the bulk ZnS band gap value of 340 nm 47 owing to the quantum confinement effect. To know about the emission behavior of these samples, we have recorded photoluminescence emission spectra by exciting the samples at their respective absorption maximum.…”

ZnS–ZnO Heterostructure Nanorings Grown under a Possible Early Earth Atmosphere

“…The combined effects of polymorphism and polarization lead to morphological variations including nanowires, 12 nanobelts, 13−18 nanosaws, 19 nanorings, 20 and even nanohelices. 21,22 Though the porous edifices constructed by ZnS precipitates and/or colloidal particles have been proposed as cradles of life, 1 we note that these one-dimensional nanostructures could offer better templates for abiogenesis. The primary reason we consider is their high surface reactivity, originating from their extremely high surface/volume ratio comparable to that of colloidal particles.…”

In situ fabrication and investigation of nanostructures and nanodevices with a microscope

“…One example is the first photo-detector designed on a single ZnS microspring constructed using manipulators which picked the required helical structures. 56 While adding optical fibres, one can investigate the optoelectronic properties of nanoscale heterostructures in more detail, i.e. an illumination position-dependent photo response may be studied (Fig.…”

“…Valuable information, such as the existence of surface oxygen vacancies and defects, as well as the efficiency of charge carrier trapping, migration and transfer, may be obtained using such experiments. 56,62 Typically, researchers excite a single sample, e.g. a microspring (Fig.…”