Variation of the Thickness and Number of Wells in the CdS/HgS/CdS Quantum Dot Quantum Well System

Abstract

We report on the first chemically prepared multilayer quantum well structure in a semiconductor quantum dot. By subsequent precipitation of HgS, CdS, HgS, and again CdS from aqueous solution, we obtained nanoparticles which contain two HgS quantum wells separated by a double layer of CdS. The core and the capping material is also CdS. The two-well system was characterized by absorption and emission spectroscopy, which clearly reveal the formation of a two-well and not a single double-layered quantum well system. This system allows to study the interaction of quantum wells that are separated by different thicknesses of the CdS barriers. The radiative and relaxation dynamics of the new two-well system are compared with the dynamics of systems having a single-layer well and a double-layer well system. † Part of the special issue "Edward W. Schlag Festschrift".

Nonparabolicity and dielectric effects on addition energy spectra of spherical nanocrystals

“…In the present paper, we consider both homogeneous HgS nanocrystals and multishell double quantum well CdS/HgS/CdS/HgS/CdS, similar to those experimentally synthesized in Ref. 24. Then, in all cases the surrounding medium of the QD is considered to be water.…”

“…Thus, in this section we consider a multishell CdS/HgS/CdS/HgS/CdS spherical QD double QW like those synthesized in Ref. 24. The parameters employed in our calculations can be found in Table I.…”

Effect of magnetic and electric fields on optical properties of semiconductor spherical layer

“…Recent advances in semiconductor technology allow growing more complex structures than the simple quantum wells, wires or dots. Among them: multiple quantum rings [1], complex quantum wires [2] and multilayered quantum dots [3][4][5]. The latter are grown using the chemical colloidal method on the basis of CdS, CdSe, ZnS, ZnSe, HgS and other semiconductor materials and are promising for many technological applications such as infrared photodetectors [6], lasers [7,8], biolabels and biosensors [9,10], etc.…”

Nanospherical heterolayer in strong electrostatic field

“…They mainly consisted of II-VI, IV-VI, and III-V compounds and can be presented, such as CdS/HgS/CdS, ZnS/CdS/ZnS, CdSe/HgSe/CdSe, CdTe/ HgTe/CdTe, CdS/PbS/CdS, PbSe/CdS/PbSe, PbSe/CdSe/ PbSe, AlAs/GaAs/AlAs/, InP/InAs/InP, etc. heterostructures (see for e.g., (Balandin and Wang 2006;Schmid 2010;Rogach 2008;Hofman 2009;Eychmuller et al 1993;Schooss et al 1994;Mews et al 1996;Hause et al 1993;Bryant 1995;Little et al 1998;Braun et al 2001;Bryant and Jaskolski 2003;Perez-Conde and Bhattacharjee 2006;Berezowsky et al 2006;Weng et al 2009;Guo-Yi 2004;Royo et al 2007;Brovelli et al 2011;Jia 2011;SalmanOgli and Roatami 2011) and references therein).The QDQW structure involves an onion-like nanosystem composed of a quantum dot core surrounded by two or more shells of alternating narrower and wider band gap materials. The original feature of QDQW is that their physical properties can be controlled and can be tuned by changing the core radius, the thickness of the quantized layer and the size of the outermost shell.…”

“…For e.g., in the CdS/ HgS/CdS QDQW structure the core of CdS (band gap of 2.5 eV) is surrounded and covered with a quantized layer of the narrower band gap material (HgS, band gap of 0.5 eV for b-HgS), which is then covered by another thick CdS layer (shell). In this composition the b-HgS layer provides a quantum well for both electrons and holes, whereas CdS core-and shell-components of the system play a role of barriers (Eychmuller et al 1993;Schooss et al 1994;Mews et al 1996;Hause et al 1993;Bryant 1995;Little et al 1998;Braun et al 2001), i.e., along the ''global'' confinement of the entire nanoparticle, the additional ''local'' confinement in the internal quantum well of the sample takes place in QDQW structures. Several experimental and theoretical investigations of this system have shown that after optical excitation the electrons and holes in this heterostructure are localized in the HgS QW (Guo-Yi 2004;Royo et al 2007;Braun et al 2002).…”