![]() The tuning of the band gap of semiconductor materials by constructing core and shell structures with different band gap, ,, play a vital role in enhancing the performance of optoelectronic devices. ![]() To broaden the applications and improve the efficiency, a variety of QDQW structures containing II–IV, IV–VI, and III–V materials are being experimentally fabricated using molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD). QDQW are widely used for applications, such as biomedical tags, light-emitting diodes, lasers, and solar cells. Semiconductor quantum dot quantum well (QDQW) structures in the recent past have received wide attention because of their interesting size-dependent optical, electronic, and magnetic properties due to the carrier confinement and surface effects. The applied electric field provides strong overlap between the electron and hole wave functions as well as increases the binding energy of the exciton, which eventually decreases the band gap. In addition, based on Quantum Confined Stark Effect (QCSE) the effect of high electric field on the charge carriers and the corresponding changes in the band gap has been investigated. The change in the band gap of QDQW is attributed to the exciton excitations by thermal occupation of the lowest dark exciton states at different temperatures. The wave function of exciton studied shows significant differences with other theory. The results of the proposed model effectively accommodates the polarization effects at the interfaces of different semiconductor materials in a core/shell/shell structure and elucidates the significant influence of interfaces on the band gap with consistency among previous theoretical and experimental results. The confinement energies of electron and hole and the Coulombic interaction energy between them are calculated for CdS/HgS/CdS, GaN/X/GaN (X=InN, In 0.33Ga 0.67 N) (QDQW) with core/shell/shell structures. , "Triplet state absorption in carbon nanotubes: A TD-DFT study", NANO LETTERS, Vol.7, iss.8, p.2201-2206, AUG 2007.A theoretical model is presented to calculate the 1s–1s transition energy of an exciton in spherically layered semiconductor quantum-dot quantum-well (QDQW), based on the LCAO variational method using effective mass approximation., "Electronic properties of DNA base molecules adsorbed on a metallic surface", JOURNAL OF PHYSICAL CHEMISTRY C, Vol.111, iss.39, p.14541-14551, OCT 4 2007., "Third and fourth optical transitions in semiconducting carbon nanotubes", PHYSICAL REVIEW LETTERS, Vol.98, iss.6, 067401, FEB 9 2007., "Determination of exciton-phonon coupling elements in single-walled carbon nanotubes by Raman overtone analysis", PHYSICAL REVIEW LETTERS, Vol.98, iss.3, 037405, JAN 19 2007., "Effect of quantum and dielectric confinement on the exciton-exciton interaction energy in type II core/shell semiconductor nanocrystals", NANO LETTERS, Vol.7, iss.1, p.108-115, JAN 2007., "Neutral radical molecules ordered in self-assembled monolayer systems for quantum information processing", Chemical Physics Letters, Vol.436, iss.1-3, p.144-149, 20070227., "Excited states and optical response of a donor-acceptor substituted polyene: A TD-DFT study", CHEMICAL PHYSICS LETTERS, Vol.433, iss.4-6, p.305-311, JAN 12 2007., "Two-photon excitation of substituted enediynes", JOURNAL OF PHYSICAL CHEMISTRY A, Vol.110, iss.1, p.241-251, JAN 12 2006., "Real-time observation of nonlinear coherent phonon dynamics in single-walled carbon nanotubes", NATURE PHYSICS, Vol.2, iss.8, p.515-520, AUG 2006., "Absorption cross sections and Auger recombination lifetimes in inverted core-shell nanocrystals: Implications for lasing performance", JOURNAL OF APPLIED PHYSICS, Vol.99, iss.3, 034309, FEB 1 2006., "Dependence of spurious charge-transfer excited states on orbital exchange in TDDFT: Large molecules and clusters", JOURNAL OF CHEMICAL THEORY AND COMPUTATION, Vol.3, iss.3, p.976-987, MAY-JUN 2007., "Excitons and peierls distortion in conjugated carbon nanotubes", NANO LETTERS, Vol.7, iss.1, p.86-92, JAN 2007., "Synthesis and characterization of amphiphilic phenylene ethynylene oligomers and their Langmuir-Blodgett films", LANGMUIR, Vol.22, iss.21, p.8813-8820, OCT 10 2006., "Photoexcited wavepacket scattering on conical intersections: Semiclassical expansion", ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, Vol.231, MAR 26 2006., "Exciton scattering and localization in branched dendrimeric structures", NATURE PHYSICS, Vol.2, iss.9, p.631-635, SEP 2006.
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