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Author Kundu, Biswajit ♦ Chakrabarti, Sudipto ♦ Pal, Amlan J.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS ♦ CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY ♦ CADMIUM SELENIDES ♦ CADMIUM SULFIDES ♦ CHARGE CARRIERS ♦ CONFINEMENT ♦ DENSITY ♦ DENSITY OF STATES ♦ ELECTRONS ♦ HOLES ♦ NANOSTRUCTURES ♦ SHELLS ♦ SPECTROSCOPY ♦ TEMPERATURE DEPENDENCE ♦ TEMPERATURE RANGE 0065-0273 K ♦ TOPOGRAPHY ♦ TUNNEL EFFECT ♦ WAVE FUNCTIONS
Abstract Core-shell nanocrystals having a type-I band-alignment confine charge carriers to the core. In this work, we choose CdSe/CdS core-shell nano-heterostructures that evidence confinement of holes only. Such a selective confinement occurs in the core-shell nanocrystals due to a low energy-offset of conduction band (CB) edges resulting in delocalization of electrons and thus a decrease in the conduction band-edge. Since the delocalization occurs through a thermal assistance, we study temperature dependence of selective delocalization process through scanning tunneling spectroscopy. From the density of states (DOS), we observe that the electrons are confined to the core at low temperatures. Above a certain temperature, they become delocalized up to the shell leading to a decrease in the CB of the core-shell system due to widening of quantum confinement effect. With holes remaining confined to the core due to a large offset in the valence band (VB), we record the topography of the core-shell nanocrystals by probing their CB and VB edges separately. The topographies recorded at different temperatures representing wave-functions of electrons and holes corresponded to the results obtained from the DOS spectra. The results evidence temperature-dependent wave-function delocalization of one-type of carriers up to the shell layer in core-shell nano-heterostructures.
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-03-14
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 119
Issue Number 10


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