Using all atom molecular dynamics (MD) simulations, we have studied the mechanical properties of ZnS/CdS core/shell nanowires. Our results show that the coating of a few atomic layer CdS shell on the ZnS nanowire leads to a significant change in the stiffness of the core/shell nanowires compared to the stiffness of pure ZnS nanowires. The binding energy between the core and shell region decreases due to the lattice mismatch at the core-shell interface. This reduction in binding energy plays an important role in determining the stiffness of a core/shell nanowire. We have also investigated the effects of the shell on the thermal conductivity and melting behavior of the nanowires.
Electronic structure and transport characteristics of coupled CdS and ZnSe quantum dots are studied using density functional theory and non equilibrium Greens function method respectively. Our investigations show that in these novel coupled dots, the frontier occupied and unoccupied molecular orbitals are spatially located in two different parts of the coupled dot, thereby indicating the possibility of asymmetry in electronic transport. We have calculated electronic transport through the coupled quantum dot by varying the coupling strength between the individual quantum dots in the limits of w…
A complex InAs/CdSe/ZnSe Core/Shell1/Shell2 (CSS) structure is synthesized, where the intermediate CdSe buffer layer decreases strain between the InAs core and the ZnSe outer shell. This structure leads to significantly improved fluorescence quantum yield as compared to previously prepared core/shell structures and enables growth of much thicker shells. The shell growth is done using a layer-by-layer method in which the shell cation and anion precursors are added sequentially allowing for excellent control and a good size distribution is maintained throughout the entire growth process. The CSS…
We considered modification of the defect density of states in CdTe as influenced by a buffer layer in ZnO(ZnS, SnSe)/CdS/CdTe solar cells. Compared to the solar cells employing ZnO buffer layers, implementation of ZnSe and ZnS resulted in the lower net ionized acceptor concentration and the energy shift of the dominant deep trap levels to the midgap of CdTe. The results clearly indicated that the same defect was responsible for the inefficient doping and the formation of recombination centers in CdTe. This observation can be explained taking into account the effect of strain on the electronic …
During the synthesis of heterostructured nanomaterials, unwanted structural and morphological changes in nanostructures may occur, especially when multiple sequential growth steps are involved. In this study, we describe a synthesis strategy of heterostructured ZnS/Al2O3/MoS2 core-shell nanowires (NWs), and explore the role of the Al2O3 interlayer during synthesis. Core-shell NWs were produced via a four-step route: 1) synthesis of ZnO NWs on a silicon wafer, 2) deposition of thin Al2O3 layer by ALD, 3) magnetron deposition of MoO3 layer, and 4) annealing of the sample in the sulphur atmospher…
Colloidal nanoplatelets (NPLs) are promising materials for lasing applications. The properties are usually discussed in the framework of 2D materials, where strong excitonic effects dominate the optical properties near the band edge. At the same time, NPLs have finite lateral dimensions such that NPLs are not true extended 2D structures. Here we study the photophysics and gain properties of CdSe/CdS/ZnS core-shell-shell NPLs upon electrochemical n doping and optical excitation. Steady-state absorption and PL spectroscopy show that excitonic effects are weaker in core-shell-shell nanoplatelets …
