TY - JOUR
T1 - Reduced carrier trapping in CdSe/ZnS/CdSe heterostructure quantum dots inferred from temperature dependent spectral studies
AU - Kushavah, Dushyant
AU - Mohapatra, Pranab Kishore
AU - Ghosh, Pintu
N1 - Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/8
Y1 - 2018/8
N2 - We report temperature dependent photoluminescence (TDPL) characteristics of CdSe/ZnS core-shell and coupled 0D-2D CdSe/ZnS/CdSe heterostructure quantum dots (HQDs). Anomalous, behavior of temperature dependent PL linewidth seen in core-shell HQDs is ascribed to the relaxation of carriers into interfacial strain related local energy minimum. TDPL characteristics show largest exciton-acoustic phonon and exciton-LO phonon coupling in core-shell HQDs compared to other QDs. These are caused by enhanced deformation potential interaction and enhanced Fröhlich interaction due to the interfacial strain field. Further, relatively lower strength of exciton-acoustic phonon coupling in 0D-2D HQDs is due to relaxation of interfacial strain. Temperature dependence of spectrally integrated PL intensity shows nonradiative relaxation below 150 K due to thermal activation of carriers in surface tarp states while at temperatures above, it is dominated by carrier thermal escape mediated by exciton-LO phonon interaction involving lesser number of phonons in 0D-2D HQDs.
AB - We report temperature dependent photoluminescence (TDPL) characteristics of CdSe/ZnS core-shell and coupled 0D-2D CdSe/ZnS/CdSe heterostructure quantum dots (HQDs). Anomalous, behavior of temperature dependent PL linewidth seen in core-shell HQDs is ascribed to the relaxation of carriers into interfacial strain related local energy minimum. TDPL characteristics show largest exciton-acoustic phonon and exciton-LO phonon coupling in core-shell HQDs compared to other QDs. These are caused by enhanced deformation potential interaction and enhanced Fröhlich interaction due to the interfacial strain field. Further, relatively lower strength of exciton-acoustic phonon coupling in 0D-2D HQDs is due to relaxation of interfacial strain. Temperature dependence of spectrally integrated PL intensity shows nonradiative relaxation below 150 K due to thermal activation of carriers in surface tarp states while at temperatures above, it is dominated by carrier thermal escape mediated by exciton-LO phonon interaction involving lesser number of phonons in 0D-2D HQDs.
KW - Carrier trapping
KW - Exciton-phonon coupling
KW - Heterostructure quantum dots
KW - Luminescence
UR - http://www.scopus.com/inward/record.url?scp=85046169737&partnerID=8YFLogxK
U2 - 10.1016/j.physe.2018.04.035
DO - 10.1016/j.physe.2018.04.035
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AN - SCOPUS:85046169737
SN - 1386-9477
VL - 102
SP - 58
EP - 65
JO - Physica E: Low-Dimensional Systems and Nanostructures
JF - Physica E: Low-Dimensional Systems and Nanostructures
ER -