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 × 10(16)  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.
authors.affiliation: Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, UK.
authors.forename: Chaw Keong
authors.initials: CK
authors.lastname: Yong
authors.forename: Hannah J
authors.initials: HJ
authors.lastname: Joyce
authors.forename: James
authors.initials: J
authors.lastname: Lloyd-Hughes
authors.forename: Qiang
authors.initials: Q
authors.lastname: Gao
authors.forename: Hark Hoe
authors.initials: HH
authors.lastname: Tan
authors.forename: Chennupati
authors.initials: C
authors.lastname: Jagadish
authors.forename: Michael B
authors.initials: MB
authors.lastname: Johnston
authors.forename: Laura M
authors.initials: LM
authors.lastname: Herz