We report on the intensity dependent exciton dynamics in optically excited tris (8-hydroxyquinoline) aluminum (Alq3) films grown by organic molecular beam epitaxy that show a strong quenching of light emission at low temperature. We further report on the mode properties in plasmonic Alq3 waveguides and on the exciton emission in InP nanowires which are coated with a thin Alq3 films and Mg:Ag metal cluster layers.
In the following study we investigate the dynamics of high aspect ratio nanowires held in a single gradient force optical trap in an overdamped environment. Power spectrum analysis performed on the stochastic trajectory of the optically trapped nanowires indicate that the motion of these nanowires shows characteristics of underdamped motion, where a broad resonance peak is present in the power spectrum of amplitude fluctuations under certain conditions. The resonance occurs when the nanowires are trapped at a height of 50 μm from the cover slip of the sample chamber. The emergence of a resonance peak in the power spectrum could be attributed to the non-conservative motion of nanowires being nonspherical, thus creating a bias towards cyclic motion as examined theoretically by Simpson and Hanna .
Accurately measuring the electronic properties of nanowires is a crucial step in the development of novel semiconductor nanowire-based devices. With this in mind, optical pump–terahertz probe (OPTP) spectroscopy is ideally suited to studies of nanowires: it provides non-contact measurement of carrier transport and dynamics at room temperature. OPTP spectroscopy has been used to assess key electrical properties, including carrier lifetime and carrier mobility, of GaAs, InAs and InP nanowires. The measurements revealed that InAs nanowires exhibited the highest mobilities and InP nanowires exhibited the lowest surface recombination velocity.
We present a novel method for spatial mapping of the luminescent properties of single optically trapped semiconductor
nanowires by combing dynamic optical tweezers with micro-photoluminescence. The technique involves the use of a
spatial light modulator (SLM) to control the axial position of the trapping focus relative to the excitation source and
collection optics. When a nanowire is held in this arrangement, scanning the axial position of the trapping beam enables
different sections of the nanowire axis to be probed. In this context we consider the axial resolution of the luminescence
mapping and optimization of the nanowire trapping by spherical aberration correction.
We report on the dynamics of micro-photoluminescence of single InP semiconductor nanowires trapped in a gradient
force optical tweezers. Nanowires studied were of zinc blende, wurtzite or mixed phase crystal poly-types and ranged in
length from one to ten micrometers. Our results show that the band-edge emission from trapped nanowires exhibits a
quenching of the initial intensity with a characteristic time scale of a few seconds and an associated spectral red shift is
also observed in the mixed phase nanowires.
The optical and structural properties of binary and ternary III-V nanowires including GaAs, InP, In(Ga)As, Al(Ga)As, and GaAs(Sb) nanowires by metal-organic chemical vapour deposition are investigated. Au colloidal nanoparticles are employed to catalyze nanowire growth. Zinc blende or wurtzite crystal structures with some stacking faults are observed for these nanowires by high resolution transmission electron microscope. In addition, the properties of heterostructure nanowires including GaAs-AlGaAs core-shell nanowires, GaAs-InAs nanowires, and GaAs-GaSb nanowires are reported. Single nanowire luminescence properties from optically bright InP nanowires are reported. Interesting phenomena such as two-temperature procedure, nanowire height enhancement of isolated ternary InGaAs nanowires, kinking effect of InAs-GaAs heterostructure nanowires, and unusual growth property of GaAs-GaSb heterostructure nanowires are investigated. These nanowires will play an essential role in future optoelectronic devices.
In this paper, techniques of quantum dot interdiffusion such as impurity free vacancy disordering and ion implantation induced disordering as well as the selective area epitaxy by metal-organic chemical vapour deposition have been used to tune the emission wavelength of self-orgainsed quantum dot structures. Under optimized experimental conditions, large differential band gap energies have been achieved by all approaches which is essential for quantum dot-based photonic integrated circuits.