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Accurate positioning of semiconductor nanowires with lasing emission at room temperature at targeted locations, onto multiple substrates and forming complex spatial patterns is demonstrated using a novel nanoscale Transfer Printing technique.
Electrical contacts between metals and semiconductors are fundamentally important for practical semiconductor devices. This work reports the electrical characterization of nanowire arrays fabricated by a top-down approach, where electron beam lithography (EBL) and a highly anisotropic Cl2/H2/Ar inductively coupled plasma (ICP) reactive ion etching (RIE) is utilised to generate vertical arrays of InP...
By combining Finite-Difference-Time-Domain simulations and the detailed-balance model of solar cell, we study how absorption efficiency determines the short circuit current density, Jsc, of single vertical nanowire (NW) solar cells. We find that due to the very high absorption efficiency, vertical NW delivers Jsc that are one order of magnitude higher than planar solar cells.
InP-InxGa(1-x)As-InP quantum well tube (QWT) structures are grown on InP nanowires that are [100] oriented. The In mole fraction, x is varied between 0 and 1. The QWTs grown on the facets of the [100] nanowires that have {100} and {011} side facets forming an octagonal cross-section, are found to be highly non-uniform. Bright emission is observed at room temperature from these QWTs. Band-gap tunability...
InP nanowire arrays have been grown and optimized using selective area epitaxy by metalorganic chemical vapour deposition technique. High quality stacking fault free wurtzite nanowires with a wide range of diameters and room temperature minority carrier lifetime as high as ∼ 1.6 ns have been obtained. An axially doped n-i-p structure was further grown and successfully fabricated into solar cell devices...
We demonstrate an optical method to evaluate the doping concentration, internal quantum efficiency (IQE) and non-radiative lifetime of semiconductor nanowires, through power dependent photoluminescence (PL) and time resolved PL (TRPL) measurement. Combining this method with standard PL and time resolved spectrum, we analyse the quality, band structure and doping distribution of Si doped InP nanowires...
We present results on the design of GaAs and InP nanowire lasers. We will discuss the growth of high quantum efficiency, taper free photonic nanowires for laser applications and demonstrate room-temperature lasing from these nanowires.
Optical pump-terahertz probe spectroscopy was used to study the key electronic properties of GaAs, InAs and InP nanowires at room temperature. Of all nanowires studied, InAs nanowires exhibited the highest mobilities of 6000 cm2V−1s−1. InP nanowires featured the longest photoconductivity lifetimes and an exceptionally low surface recombination velocity of 170 cm/s.
In this paper we present our progress towards the opto-electronic characterization of indium phosphide (InP) nanowire transistors at milli-Kelvin temperatures. First, we have investigated the electronic transport of the InP nanowires by current-voltage (I–V) spectroscopy as a function of temperature from 300 K down to 40 K. Second, we show the successful operation of a red light emitting diode (LED)...
A systematic growth temperature study has been performed to achieve high quality InP nanowires (NWs) by selective-area metal-organic vapour-phase epitaxy (SA-MOVPE). The optical quality of these nanowires was evaluated from time-resolved photoluminescence (TRPL) at 300 K.
InP nanowires (NWs) are grown on Si substrate using a thin inter-mediate buffer layer. The buffer layer is grown in two steps. An initial nucleation layer is crucial to accommodate the lattice mismatch between InP and Si. A high quality 2nd layer is grown on this initial layer with smooth morphology suitable for the NW growth. More than 97% vertical yield is achieved on the buffer layer and the morphology...
We review GaAs and InP nanowires and GaAs based nanowire heterostructures grown on (111)B substrates by metal organic chemical vapor deposition via vapor-liquid-solid (VLS) mechanism. Transmission electron microscopy, time-resolved photoluminescence and micro-Raman spectroscopy have been used to understand the crystal structure, carrier lifetime and strain effects on the bandgap energy.
We report the growth of InP/InGaAs core-shell nanowires by metal organic chemical vapour deposition (MOCVD). The grown nanowires are distributed uniformly and are vertical to the substrate. The coreshell nanowires have been structurally characterised by scanning electron microscopy and transmission electron microscopy.
Mid-infrared emission with high efficiency was achieved for InAsSb quantum dots by using InGaAsSb sandwich layers and InP carrier blocking layers. As a result of reduced quantum confinement and lattice mismatch around InAsSb quantum dots caused by InGaAsSb layers, an emission of 2.1 μm was obtained for the sample with In0.53Ga0.47As0.25Sb0.75 layers. The emission signal was observed up to 330 K by...
In this work, controlled band gap modifications in AlInGaAs/InGaAs quantum well structures using different encapsulating layers are studied and compared. X-ray photoelectron spectroscopy was used to investigate the interfacial reaction between the quantum well structure and dielectric capping layer.
Growth of Au-catalyzed InP nanowires (NWs) by metalorganic chemical vapor deposition (MOCVD) has been studied in the temperature range of 400-510°C and V/III ratio of 44-700. We demonstrate that minimal tapering of InP NWs can be achieved at 400°C and V/III ratio of 350. Zinc-blende (ZB) or wurtzite (WZ) NWs is obtained depending on the growth conditions. 4K microphotoluminescence (μ-PL) studies show...
We report the effect of V/III ratio and nanowire diameter on the crystal structure and optical properties of InP nanowires. Time -resolved photoluminescence studies have revealed that wurtzite nanowires show longer carrier lifetimes than zinc-blende ones.
GaAs and InP based nanowires were grown epitaxially on GaAs or InP (111)B substrates by MOCVD via VLS mechanism. In this paper, I will give an overview of nanowire research activities in our group.
GaAs and InP based nanowires were grown epitaxially on GaAs or InP (111)B substrates by metalorganic chemical vapor deposition using Au nanoparticles as catalyst. In this talk, I will give an overview of nanowire research activities in our group. Especially, the effects of growth parameters for GaAs and InP nanowires on the crystal quality have been studied in detail. We demonstrated the ability to...
InP and GaAs based nanowires were grown epitaxially on InP or GaAs (111)B substrates by metalorganic chemical vapor deposition via vapor-liquid-solid (VLS) mechanism. In this report, I will give an overview of nanowire research activities in our group. In particular, the effects of growth parameters for InP and GaAs nanowires on the crystal quality have been studied in detail. We demonstrated the...
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