Bent Polytypic ZnSe and CdSe Nanowires Probed by Photoluminescence

Abstract

Nanowires (NWs) have witnessed tremendous development over the past two decades owing to their varying potential applications. Semiconductor NWs often contain stacking faults due to the presence of coexisting phases, which frequently hampers their use. Herein, it is investigated how stacking faults affect the optical properties of bent ZnSe and CdSe NWs, which are synthesized using the vapor transport method. Polytypic zinc blende-wurtzite structures are produced for both these NWs by altering the growth conditions. The NWs are bent by the mechanical buckling of poly(dimethylsilioxane), and micro-photoluminescence (PL) spectra were then collected for individual NWs with various bending strains (0-2%). The PL measurements show peak broadening and red shifts of the near-band-edge emission as the bending strain increases, indicating that the bandgap decreases with increasing the bending strain. Remarkably, the bandgap decrease is more significant for the polytypic NWs than for the single phase NWs. This work provides insights into flexible electronic devices of 1D nanostructures by engineering the polytypic structures.

Strain Mapping and Raman Spectroscopy of Bent GaP and GaAs Nanowires

“…It has been observed that the emission of bent (or buckled) NWs red shifts due to a piezoelectric field. 9−13 We predict that the band gap of the bent GaP and GaAs NWs would decrease owing to the dominant tensile strain. Furthermore, the larger excessive tensile strain of GaAs NWs suggests the larger band gap decrease as compared to that of GaP NWs.…”

“…2−8 For bent (or buckled) NWs, a red-shifted emission has been observed, which has been explained by the piezotronic effect, in which under a piezoelectric field, the number of photons emitted from the outer surface of the NW is much larger than that from the inner surface. 9−13 The outstanding piezoelectric properties of ZnO and CdS NWs have facilitated the development of various piezotronic and piezo-phototronic devices such as nanogenerators, field-effect transistors, and light-emitting diodes, which rely on the piezoelectric potential created along the strained NWs. 3,14−16 Moreover, the enhanced carrier mobility or photocurrent of strained NWs has attracted widespread research interest owing to their great potential in a rich variety of applications.…”

Recent advances in low‐dimensional semiconductor nanomaterials and their applications in high‐performance photodetectors

“…Different materials in the II‐VI compound have different bandgaps, such as 1.5 eV for CdTe, 3.7 eV for ZnS, and the like. This makes them ideal for optoelectronic devices at different wavelengths . ZnO is one of the most widely studied materials in oxide semiconductors (II‐VI) .…”

“…This makes them ideal for optoelectronic devices at different wavelengths. 101,102 ZnO is one of the most widely studied materials in oxide semiconductors (II-VI). 66,92,103-107 ZnO has very good semiconductor properties with wide direct bandgap and unique piezoelectric and mechanical properties, which make ZnO have many applications, such as PDs, solar photovoltaics, flexible electronics, and so on.…”

One-Step Synthesis of Enhanced Band-Edge Emission ZnSe Nanowires Assisted by SnO<SUB>2</SUB>

“…Zinc selenide (ZnSe) is an important II-VI semiconductor material with a direct band-gap of ~2.7 eV at room temperature, which is widely regarded as a very good candidate for blue-violet light emitting devices [1] [2] [3] [4]. With the miniaturization of devices, many research groups have begun to study the nanostructures of ZnSe materials and have done a lot of work in this area.…”