We demonstrate the utility of optical second harmonic generation (SHG) polarimetry to perform structural characterization of noncentrosymmetric, single-crystalline II-VI semiconducting nanowires, nanobelts, and nanoflakes. By analyzing anisotropic SHG polarimetric patterns, we distinguish between wurtzite and zincblende II-VI semiconducting crystal structures and determine their growth orientation. The crystallography of these nanostructures was then confirmed via transmission electron microscopy measurements performed on the same system. In addition, we show that some intrinsic material properties such as nonlinear coefficients and geometry-dependent optical in-coupling coefficients can also be determined from the SHG experiments in WZ nanobelts. The ability to perform SHG-based structural characterization and crystallographic study of II-VI semiconducting single-crystalline nanomaterials will be useful to correlate structure-property relationships of nanodevices on which transmission electron microscopy measurements cannot be typically performed.
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http://dx.doi.org/10.1021/acs.nanolett.5b02690 | DOI Listing |
ACS Omega
October 2024
Northwest Institute for Nonferrous Metal Research, Xi'an 710016, China.
In this work, CdSe was taken as the representation to systematically investigate the (111) and (110) surface reconstructions, the electronic properties transition related to the layer size, and the corresponding physical mechanism through the density functional theory (DFT) calculation. For the (111) surface slab structure, the bulk truncated relaxation (BTR) surface and the honeycomb (HC) surface were carefully examined. The HC surface configuration, ignored by previous studies, is an energetically preferred surface compared to both the as-truncated and BTR configurations.
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October 2022
Department of Chemistry, Quaid-I-Azam University, Islamabad 45320, Pakistan.
Quantum dots (QDs) are semiconducting nanocrystals that exhibit size- and composition-dependent optical and electronic properties. Recently, Cu-based II-VI ternary Cu Cd S (CCS) QDs have emerged as a promising class of QDs as compared to their binary counterparts (CuS and CdS). Herein, a series of ternary CCS QDs are synthesized by changing the molar concentration of Cu ions only keeping the 1:1 ratio of the stoichiometric mixture of Cd and S.
View Article and Find Full Text PDFPhys Chem Chem Phys
October 2022
Electrochemical Power Sources Division, CSIR Central Electrochemical Research Institute, Karaikudi-630003, Tamil Nadu, India.
By employing first principles density functional theory calculations on thickness dependent structural and electronic properties of (0001) surface slabs of wurtzite MX compounds, our study demonstrated the possibility of the existence of 2D layered materials from II-VI group traditional semiconducting compounds that are widely used in various fields. Our calculations revealed that (0001) surface slabs of wurtzite ZnO and CdO compounds prefer to stabilize as sp hybridized - atomically thin graphitic layers as observed in earlier work, which are separated by van der Waals distances, when compared to the respective wurtzite slabs. On the other hand, for surface slabs of other ZnX and CdX (X = S, Se, Te) compounds, sp hybridized bilayers, which comprise an X-Zn(Cd)-Zn(Cd)-X structural arrangement, are energetically stable until certain thicknesses of the slabs.
View Article and Find Full Text PDFSci Rep
October 2021
CENTERA Laboratories, Institute of High Pressure Physics, Polish Academy of Sciences, 01-142, Warsaw, Poland.
The search for exotic new topological states of matter in widely accessible materials, for which the manufacturing process is mastered, is one of the major challenges of the current topological physics. Here we predict higher order topological insulator state in quantum wells based on the most common semiconducting materials. By successively deriving the bulk and boundary Hamiltonians, we theoretically prove the existence of topological corner states due to cubic symmetry in quantum wells with double band inversion.
View Article and Find Full Text PDFACS Nano
September 2021
CNRS, Univ. Bordeaux, Bordeaux INP, ICMCB, UMR 5026, 87 avenue du Dr. A. Schweitzer, Pessac F-33608, France.
Metal/semiconductor hetero-nanostructures are now considered as benchmark functional nanomaterials for many light-driven applications. Using laser-driven photodeposition to control growth of gold nanodots (NDs) onto CdSe/CdS dot-in-rods (DRs), we show that the addition of a dedicated hole scavenger (MeOH) is cornerstone to significantly reduce to less than 3.5% the multiple-site nucleation and 2.
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