نتایج جستجو برای: band gap engineering
تعداد نتایج: 516322 فیلتر نتایج به سال:
In this paper the effect of photonic band gap on the group velocity of reflected pulse from a dielectric slab doped with two-level or three-level atoms has been investigated. It is assumed that the slab is sandwiched between a uniform medium (like vacuum) and a one-dimensional photonic crystal. It is shown that the reflected pulse from the slab doped with two-level (three-level) atoms will be...
We demonstrate a new band engineering strategy for the design of semiconductor perovskite ferroelectrics for photovoltaic and other applications from first principles. We study six ferroelectric solid solutions created by partially substituting Zn2+ for Nb5+ into the parent KNbO3 material, combined with charge compensation at the A sites with different combinations of higher valence cations. Ou...
SiO2/ZnS core/shell nanostructures have been synthesized at room temperature by a simple wet chemical method. The prepared materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR), UV–vis spectroscopic and transmission electron microscopy (TEM) studies. X-ray diffraction pattern exhibits peaks correspond to the cubic phase of ZnS. Th...
Controlling the band gap by tuning the lattice structure through pressure engineering is a relatively new route for tailoring the optoelectronic properties of two-dimensional (2D) materials. Here, we investigate the electronic structure and lattice vibrational dynamics of the distorted monolayer 1T-MoS2 (1T') and the monolayer 2H-MoS2 via a diamond anvil cell (DAC) and density functional theory...
The structure and the electronic properties of single-walled zigzag BN and B3C2N3 nanotubes (n, 0; n=4–10) were investigated using first-principles calculations based on a density functional theory. A plane–wave basis set with periodic boundary conditions in conjunction with Vanderbilt ultrasoft pseudo-potential was employed. The energy gap of ZB3C<su...
The analogy between electromagnetic wave propagation in multidimensionally periodic structures and electronwave propagation in real crystals has proven to be a fruitful one. Initial efforts were motivated by the prospect of a photonic band gap, a frequency band in three-dimensional dielectric structures in which electromagnetic waves are forbidden irrespective of the propagation direction in sp...
Materials and structures that strongly discriminate electromagnetic radiation based on one, or more of its properties (e.g. polarization, frequency) play an enabling role for a wide range of physical phenomena. For example, polarizers can selectively transmit light based on its polarization [1] over a wide range of frequencies; photonic crystals [2] (PhCs) can reflect light of certain frequenci...
the stable configurations, electronic structure and magnetic properties of b16n16, b8c24, al and p inserted (bc3)8 was studied by performing density functional theory (dft) calculations of the nmr parameters. the results indicate that b8c24 has semiconductivity property and be effectively modified by inserting groups due to the introduction of certain impurity states within the band gap of the ...
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