We calculated the energy eigenvalues of carriers in rectangular QUANTUM wires and QUANTUM cubes with finite barrier potential using the envelope function approximation. Ga0.47 In0.53 As / InP and GaAs /Ga0.63 Al0.37 As systems are considered, and a term corresponding to the variation of carriers effective mass at the boundaries is also included in the envelope function. The calculated energy levels are lower than those previously reported, and are in better agreement with the experimental results.

Two-dimensional semiconductor QUANTUM-dot systems are typical nanoscale structures in which a few number of electrons is confined in a small region of space by applying external electric gate potentials. While the detailed form of the confining potential depends on the specific experimental setup, the parabolic CONFINEMENT model has commonly been used because of its simplicity. Clearly, on those instances in which the experimental setup involves placement of gate potentials with sharp geometric features, the area depleted of electrons; thus, the QUANTUM-dot region cannot be considered circular. If, for simplicity, we consider the CONFINEMENT region of the electrons as square in shape, then an accurate calculation of the properties of such square-patterned QUANTUM dot should be made using a realistic CONFINEMENT potential originating from that particular configuration. We calculated exactly such a CONFINEMENT potential for a square QUANTUM dot. The particular analytic form of this realistic potential is complicated given its dependence on the two-dimensional position coordinates, rather than simply the distance from the center of the QUANTUM dot. In this work, we choose to substitute the realistic CONFINEMENT potential for a square-patterned QUANTUM dot with an approximated circular symmetric potential. We assess the quality of this approximation and discuss instances in which one can reliably use the approximated simplified potential instead of the computationally unyielding exact one.

QUANTUM dots (QDs) can be defined as nanoparticles (NPs) in which the movement of charge carriers is restricted in all directions. CdTe QDs are one of the most important semiconducting crystals among other various types where it has a direct energy gap of about 1.53 eV. The aim of this study is to exaine the optical and structural properties of the 3MPA capped CdTe QDs. The preparation method was based on the work of Ncapayi et al. for preparing 3MPA CdTe QDs, and hen, the same way was treated as by Ahmed et al. via hydrothermal method by using an autoclave at the same temperature but at a different reaction time. The direct optical energy gap of CdTe QDs is between 2.29 eV and 2.50 eV. The FTIR results confirmed the covalent bonding between the 3 MPA ligands and the QDs surface. The XRD results revealed that the synthesized QDs have two crystal structures, wurtzite and cubic zinc blend. FESEM results confirmed that the NPs have a spherical shape with an average diameter of nearly 33.85 nm. TEM analysis confirmed the particle's near sphericity, with an average diameter of around 49.33 nm. The sudden increase in temperature led to increase the particle size. It was found that ligand addition, maintaining the solution's acidity, and autoclaving the material enhanced QUANTUM CONFINEMENT.

In this work, we report, optical properties of Cd1-xSnxTe QUANTUM dots (x= 0.05, 0.10 and 0.15) synthesized in water using thioglycolic acid (TGA) as a modifier agent. The optical characterization of the samples was performed through absorption (UV) and photoluminescence spectra (PL). A red shift absorption and fluorescent emission peaks was observed which can be related to the increase of nanocrystals diameter with pass the reaction time. This size dependent phenomenon is concerned to the known “QUANTUM CONFINEMENT” effect and the highest QUANTUM yield has been achieved under our experimental conditions (using thioglycolic acid (TGA) as a modifier agent) when the processing time reached to 150 min.