Second-order nonlinear optical susceptibility for gapped graphene (original) (raw)
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This paper presents experimental and density functional theory (DFT) investigations of Zn doping role in the Zn@CdO ternary system. Zn doped CdO nanostructures with different Zn concentrations were successfully casted on glass substrates by sol-gel spin coating method. Cubic Zn@CdO structured ternary alloyed nanostructures thin films with 0.0%, 1.0%, 2.0% and 3.0% wt. Zn concentrations were obtained. An enhancement in the lateral growth of CdO cauliflower-like nanostructures was observed after Zn addition which leads to a 2D growth of nanostructured films with improved continuity. The effect of Zn doping on the linear optical parameters such as the optical band gap, the absorption index and the refractive index were also investigated. A remarkable blue shift in the band edge was observed as Zn is incorporated into the CdO matrix. In addition, the third order nonlinear optical parameters χ(3) and n2 were calculated and found to be about 2.89×10-12 - 4.33×10-14 esu and 2.89×10-12 - 4....
Metal−organic frameworks (MOFs) have been intensively studied over the past decade because they represent a new category of hybrid inorganic-organic materials with extensive surface areas, ultrahigh porosity, along with the extraordinary tailorability of structure, shape and dimensions. In this highlight, we summarize the current state of MOF research and report on structure−property relationships for nonlinear optical (NLO) and dielectric applications. We focus on the design principles and structural elements needed to develop potential NLO and low dielectric (low-κ) MOFs with an emphasis on enhancing material performance. In addition, we highlight experimental evidence for the design of devices for low-dielectric applications. These results motivate us to develop better low-dielectric and NLO materials and to perform in-depth studies related to deposition techniques, patterning and the mechanical performance of these materials in the future.
Фізика і хімія твердого тіла, 2021
Zinc blende (ZB) and wurtzite (WZ) structure of cadmium selenide (CdSe) is determined using densityfunctional theory within local density approximation (LDA), generalized gradient approximation (GGA), Hubbardcorrection (GGA + U) and Hybrid functional approximation (PBE0 or HSE06). The convergence test of total energy with respect to cutoff energy and k-point sampling is performed to assure the accuracy of calculation. The equilibrium lattice constant of CdSe in both phases are calculated and the obtained values are in good agreement with experimental values. The calculated band gap values of CdSe in WZ and ZB phase are severely underestimated. However, the band gap values obtained by using GGA + U and the hybrid functional approximations are consistent with the experimental results. Optical properties: complex and real parts of dielectric function, energy loss spectrum and absorption coefficient of CdSe in both ZB and WZ phase were studied. The calculated static dielectric constant ε 1 (0) of ZB CdSe is 11.7595, 13.7050 and 8.2099 for LDA, PBE and DFT + U approximations respectively. The value obtained using Hubbard correction is consistent with the experimental result. Moreover, the static dielectric constant ε 1 (0) of WZ CdSe is 8.1211, 5.3536 and 4.2133 for LDA, PBE and DFT + U approximations in that order. The optical absorption spectrums of both phases have several peaks which correspond to different electronic transitions from occupied to unoccupied band. However, the loss function describes the loss of energy while traversing through the material.
Effects of disorder on the optical gap of (Zn,Mg)(S,Se)
Applied Physics Letters, 1999
The electronic and optical properties of (Zn,Mg)(S,Se) wide-gap solid solutions are studied using ab initio techniques and starting from the previously determined atomistic structure of the alloy. Compositional disorder is shown to close substantially the gap with respect to the predictions of the virtual-crystal approximation. The bowing of the fundamental gap vs. composition predicted by our calculations is in very good agreement with experiments available for the Zn(S,Se) pseudo-binary alloy. At temperatures typical for MBE growth, the quaternary alloy displays a rather large amount of short-range order whose effect is to slightly but unmistakably open the gap. Our results agree well with recent experimental data for the quaternary alloy.