title: Emergence of localized states in narrow GaAs/AlGaAs nanowire quantum well tubes.
abstract: We use low-temperature photoluminescence, photoluminescence excitation, and photoluminescence imaging spectroscopy to explore the optical and electronic properties of GaAs/AlGaAs quantum well tube (QWT) heterostructured nanowires (NWs). We find that GaAs QWTs with widths >5 nm have electronic states which are delocalized and continuous along the length of the NW. As the NW QWT width decreases from 5 to 1.5 nm, only a single electron state is bound to the well, and no optical excitations to a confined excited state are present. Simultaneously, narrow emission lines (fwhm < 600 μeV) appear which are localized to single spatial points along the length of the NW. We find that these quantum-dot-like states broaden at higher temperatures and quench at temperatures above 80 K. The lifetimes of these localized states are observed to vary from dot to dot from 160 to 400 ps. The presence of delocalized states and then localized states as the QWTs become more confined suggests both opportunities and challenges for possible incorporation into quantum-confined device structures.
authors.affiliation: Department of Physics, University of Cincinnati , Cincinnati, Ohio 45221-0011, United States.
authors.forename: Teng
authors.initials: T
authors.lastname: Shi
authors.forename: Howard E
authors.initials: HE
authors.lastname: Jackson
authors.forename: Leigh M
authors.initials: LM
authors.lastname: Smith
authors.forename: Nian
authors.initials: N
authors.lastname: Jiang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Gao
authors.forename: H Hoe
authors.initials: HH
authors.lastname: Tan
authors.forename: Chennupati
authors.initials: C
authors.lastname: Jagadish
authors.forename: Changlin
authors.initials: C
authors.lastname: Zheng
authors.forename: Joanne
authors.initials: J
authors.lastname: Etheridge
keywords: Nanowires; excitation spectroscopy; heterostructures; quantum well