Band alignment of Cd(1-x)ZnxS produced by spray pyrolysis method

The impact of strain on the optical properties of semiconductor quantum dots (QDs) is fundamentally important while still awaiting detailed investigation. CdTe/CdS core/shell QDs represent a typical strained system due to the substantial lattice mismatch between CdTe and CdS. To probe the strain-related effects, aqueous CdTe/CdS QDs were synthesized by coating different sized CdTe QD cores with CdS shells upon the thermal decomposition of glutathione as a sulfur source under reflux. The shell growth was carefully monitored by both steady-state absorption and fluorescence spectroscopy and transient fluorescence spectroscopy. In combination with structural analysis, the band alignments as a consequence of the strain were modified based on band deformation potential theory. By further taking account of these strain-induced band shifts, the effective mass approximation (EMA) model was modified to simulate the electronic structure, carrier spatial localization, and electron–hole wave function overlap for compa...

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Insight into Strain Effects on Band Alignment Shifts, Carrier Localization and Recombination Kinetics in CdTe/CdS Core/Shell Quantum Dots

https://sciold.ui.ac.ir/~sjalali/papers/P2013.2.pdf

Conversion of optically isotropic to anisotropic CdSxSe1−x (0 ⩽ x ⩽ 1) alloy with S concentration

First principles calculations of Cd and Zn chalcogenides with modified Becke-Johnson density potential

The state-of-the-art all-electron full potential linear augmented plane wave based on density functional theory was applied for calculating the structural, electronic band structure, effective mass, density of state, and valence electron charge density of AA- and AB-stacking of carbon nitride (C3N4). Calculations were performed using four schemes, namely local density approximation (LDA-CA) by Ceperley–Alder, generalized gradient approximation developed by Perdew Burke and Ernzerhof (GGA-PBE), Engel–Vosko generalized gradient approximation (EV-GGA) and the recently developed modified Becke–Johnson (mBJ) potentials. The calculated band structure and total density of states verify the semiconducting nature of the two configurations with band gap of about 2.589 eV and 2.990 eV for AA- and AB-stacking of C3N4. The effective mass ratio of electron, heavy hole and light hole were calculated for both AA- and AB-stacking. The upper valence band in AB-stacking is much flatter as compared to AA-stacking, and elucidates a dramatic increase in the effective mass ratio of heavy holes which cause a reduction in group velocity of the wave packet and consequently decrease the mobility of the charge carrier. The partial density of state shows the variation in the orbital state and its strength as one moves from AA- to AB-stacking. The strong hybridization among the orbitals of both stacking (AA- and AB-) shows covalent nature of the bonds. The calculated valence electron charge density contour shows the prevailing covalent nature of C and N bonds with negligible percentage (8.08%) of ionicity.

Özden Akıncı

Papers

First principles calculations of Cd and Zn chalcogenides with modified Becke-Johnson density potential

Semiempirical tight binding modeling of Cd based II-VI heterostructures for solar cells

Semi-empirical tight binding modelling of CdSTe/CdTe, ZnSSe/ZnSe and ZnSSe/ CdSe heterostructures

Tight binding modeling of CdSe/ZnS and CdZnS/CdS II–VI heterostructures for solar cells: Role of d-orbitals

Modelling of bandgap and band offset properties in III-N related heterostructures