Ultrafast dynamics of exciton formation in semiconductor nanowires

Chaw Keong Yong; Hannah J. Joyce; James Lloyd-Hughes; Qiang Gao; Hark Hoe Tan; Chennupati Jagadish; Michael B. Johnston; Laura M. Herz

doi:10.1002/smll.201200156

Ultrafast dynamics of exciton formation in semiconductor nanowires

Chaw Keong Yong
, Hannah J. Joyce
, James Lloyd-Hughes
, Qiang Gao
, Hark Hoe Tan
, Chennupati Jagadish
, Michael B. Johnston
, Laura M. Herz^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

19 Citations (Scopus)

Abstract

The dynamics of free electron-hole pairs and excitons in GaAs-AlGaAs-GaAs core-shell-skin nanowires is investigated using femtosecond transient photoluminescence spectroscopy at 10 K. Following nonresonant excitation, a bimolecular interconversion of the initially generated electron-hole plasma into an exciton population is observed. This conducting-to-insulating transition appears to occur gradually over electron-hole charge pair densities of 2-4 × 10¹⁶ cm^-3. The smoothness of the Mott transition is attributed to the slow carrier-cooling during the bimolecular interconversion of free charge carriers into excitons and to the presence of chemical-potential fluctuations leading to inhomogeneous spectral characteristics. These results demonstrate that high-quality nanowires are model systems for investigating fundamental scientific effects in 1D heterostructures.

Original language	English
Pages (from-to)	1725-1731
Number of pages	7
Journal	Small
Volume	8
Issue number	11
DOIs	https://doi.org/10.1002/smll.201200156
Publication status	Published - 11 Jun 2012

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title = "Ultrafast dynamics of exciton formation in semiconductor nanowires",

abstract = "The dynamics of free electron-hole pairs and excitons in GaAs-AlGaAs-GaAs core-shell-skin nanowires is investigated using femtosecond transient photoluminescence spectroscopy at 10 K. Following nonresonant excitation, a bimolecular interconversion of the initially generated electron-hole plasma into an exciton population is observed. This conducting-to-insulating transition appears to occur gradually over electron-hole charge pair densities of 2-4 × 1016 cm-3. The smoothness of the Mott transition is attributed to the slow carrier-cooling during the bimolecular interconversion of free charge carriers into excitons and to the presence of chemical-potential fluctuations leading to inhomogeneous spectral characteristics. These results demonstrate that high-quality nanowires are model systems for investigating fundamental scientific effects in 1D heterostructures.",

keywords = "charge plasma, excitons, nanowires, photoluminescence, ultrafast spectroscopy",

author = "Yong, \{Chaw Keong\} and Joyce, \{Hannah J.\} and James Lloyd-Hughes and Qiang Gao and Tan, \{Hark Hoe\} and Chennupati Jagadish and Johnston, \{Michael B.\} and Herz, \{Laura M.\}",

year = "2012",

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doi = "10.1002/smll.201200156",

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TY - JOUR

T1 - Ultrafast dynamics of exciton formation in semiconductor nanowires

AU - Yong, Chaw Keong

AU - Joyce, Hannah J.

AU - Lloyd-Hughes, James

AU - Gao, Qiang

AU - Tan, Hark Hoe

AU - Jagadish, Chennupati

AU - Johnston, Michael B.

AU - Herz, Laura M.

PY - 2012/6/11

Y1 - 2012/6/11

N2 - The dynamics of free electron-hole pairs and excitons in GaAs-AlGaAs-GaAs core-shell-skin nanowires is investigated using femtosecond transient photoluminescence spectroscopy at 10 K. Following nonresonant excitation, a bimolecular interconversion of the initially generated electron-hole plasma into an exciton population is observed. This conducting-to-insulating transition appears to occur gradually over electron-hole charge pair densities of 2-4 × 1016 cm-3. The smoothness of the Mott transition is attributed to the slow carrier-cooling during the bimolecular interconversion of free charge carriers into excitons and to the presence of chemical-potential fluctuations leading to inhomogeneous spectral characteristics. These results demonstrate that high-quality nanowires are model systems for investigating fundamental scientific effects in 1D heterostructures.

AB - The dynamics of free electron-hole pairs and excitons in GaAs-AlGaAs-GaAs core-shell-skin nanowires is investigated using femtosecond transient photoluminescence spectroscopy at 10 K. Following nonresonant excitation, a bimolecular interconversion of the initially generated electron-hole plasma into an exciton population is observed. This conducting-to-insulating transition appears to occur gradually over electron-hole charge pair densities of 2-4 × 1016 cm-3. The smoothness of the Mott transition is attributed to the slow carrier-cooling during the bimolecular interconversion of free charge carriers into excitons and to the presence of chemical-potential fluctuations leading to inhomogeneous spectral characteristics. These results demonstrate that high-quality nanowires are model systems for investigating fundamental scientific effects in 1D heterostructures.

KW - charge plasma

KW - excitons

KW - nanowires

KW - photoluminescence

KW - ultrafast spectroscopy

UR - https://www.scopus.com/pages/publications/84861854591

U2 - 10.1002/smll.201200156

DO - 10.1002/smll.201200156

M3 - Article

SN - 1613-6810

VL - 8

SP - 1725

EP - 1731

JO - Small

JF - Small

IS - 11

ER -

Ultrafast dynamics of exciton formation in semiconductor nanowires

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