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Title: Spectroscopy and dynamics of charge transfer excitons in type-II band aligned quantum confined heterostructures

We illustrate effect of charge transfer (CT) in type-II quantum confined heterostructure by comparing CdSe quantum dots (QDs), CdSe/CdTe heterostructure quantum dots (HQDs) and CdSe/CdTe/CdSe quantum well-quantum dots (QWQDs) heterostructures. CdSe core QDs were synthesized using a kinetic growth method where QD size depends on reaction time. For shell coating we used modified version of successive ionic layer adsorption and reaction (SILAR). Size of different QDs ∼5 to 7 nm were measured by transmission electron microscopy (TEM). Strong red shift from ∼597 to ∼746 nm in photoluminescence (PL) spectra from QDs to QWQDs shows high tunability which is not possible with single constituent semiconductor QDs. PL spectra have been recorded at different temperatures (10K-300K). Room temperature time correlated single photon counting (TCSPC) measurements for QDs to QWQDs show three exponential radiative decay. The slowest component decay constant in QWQDs comes around eight fold to ∼51 ns as compared to ∼6.5 ns in HQD suggesting new opportunities to tailor the radiative carrier recombination rate of CT excitons.
Authors:
 [1] ; ; ;  [2] ;  [3] ;  [4]
  1. Centre for Research in Nanotechnology and Science, IIT Bombay-400076, Mumbai (India)
  2. Department of physics, IIT Bombay, Mumbai-400076 (India)
  3. Indian Institute of Science Education and Research Bhopal-462066, Bhopal (India)
  4. Department of Metallurgical Engineering and Materials Science, IIT Bombay, Mumbai-400076 (India)
Publication Date:
OSTI Identifier:
22391756
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1661; Journal Issue: 1; Conference: ICCMP 2014: International Conference on Condensed Matter Physics 2014, Shimla (India), 4-6 Nov 2014; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 77 NANOSCIENCE AND NANOTECHNOLOGY; ADSORPTION; CADMIUM SELENIDES; CADMIUM TELLURIDES; COMPARATIVE EVALUATIONS; EMISSION SPECTRA; EMISSION SPECTROSCOPY; EXCITONS; HETEROJUNCTIONS; LAYERS; PHOTOLUMINESCENCE; PHOTONS; QUANTUM DOTS; QUANTUM WELLS; RADIATIVE DECAY; RECOMBINATION; RED SHIFT; SEMICONDUCTOR MATERIALS; TEMPERATURE RANGE 0273-0400 K; TRANSMISSION ELECTRON MICROSCOPY