Growth Of III-V Semiconductor Nanowires Research Articles

Revealing charge carrier dynamics and transport in Te-doped GaAsSb and GaAsSbN nanowires by correlating ultrafast terahertz spectroscopy and optoelectronic characterization

Recent advances in the growth of III-V semiconductor nanowires (NWs) hold great promise for nanoscale optoelectronic device applications. It is established that a small amount of nitrogen (N) incorporation in III-V semiconductor NWs can effectively red-shift their wavelength of operation and tailor their electronic properties for specific applications. However, understanding the impact of N incorporation on non-equilibrium charge carrier dynamics and transport in semiconducting NWs is critical in achieving efficient semiconducting NW devices. In this work, ultrafast optical pump-terahertz probe spectroscopy has been used to study non-equilibrium carrier dynamics and transport in Te-doped GaAsSb and dilute nitride GaAsSbN NWs, with the goal of correlating these results with electrical characterization of their equilibrium photo-response under bias and low-frequency noise characteristics. Nitrogen incorporation in GaAsSb NWs led to a significant increase in the carrier scattering rate, resulting in a severe reduction in carrier mobility. Carrier recombination lifetimes of 33 ± 1 picoseconds (ps) and 147 ± 3 ps in GaAsSbN and GaAsSb NWs, respectively, were measured. The reduction in the carrier lifetime and photoinduced optical conductivities are due to the presence of N-induced defects, leading to deterioration in the electrical and optical characteristics of dilute nitride NWs relative to the non-nitride NWs. Finally, we observed a very fast rise time of ∼2 ps for both NW materials, directly impacting their potential use as high-speed photodetectors.

Phase Control Growth of InAs Nanowires by Using Bi Surfactant

To realize practical applications of nanowire-based devices, it is critical, yet challenging, to control crystal structure growth of III-V semiconductor nanowires. Here, we demonstrate that controlled wurtzite and zincblende phases of InAs nanowires can be fabricated using bismuth (Bi) as a surfactant. For this purpose, catalyst free selective area epitaxial growth of InAs nanowires was performed using molecular beam epitaxy (MBE). During the growth, Bi was used which may act as a wetting agent influencing the surface energy at growth plane ends, promoting wurtzite crystal phase growth. For a demonstration, wurtzite and zincblende InAs nanowires were obtained with and without using Bi-flux. Photoluminescence spectroscopy (PL) analysis of the nanowires indicates a strong correlation between wurtzite phase and the Bi-flux. It is observed that the bandgap energy of wurtzite and zincblende nanowires are ∼0.50 eV and ∼0.42 eV, respectively, and agree well with theoretical estimated bandgap of corresponding InAs crystal phases. A blue shift in PL emission peak energy was found with decreasing nanowire diameter. The controlled wurtzite and zincblende crystal phase and its associated heterostructure growth of InAs nanowires on Si may open up new opportunities in bandgap engineering and related device applications integrated on Si. Furthermore, this work also illustrates that Bi as a surfactant could play a dynamic role in the growth mechanism of III-V compound semiconductors.

Branched InAs nanowire growth by droplet confinement

Anisotropy in crystal growth of III-V semiconductor nanowires can be enhanced by the assistance of a liquid particle. During the past decades, selected scientific works have reported a controlled change in the nanowire growth direction by manipulation of the assisting droplet. Although these results are interesting from an engineering point of view, a detailed understanding of the process is necessary in order to rationally design complex nanostructures. In this letter, we utilize our understanding of the growth-assisting droplet to control the morphology and direction of gold-assisted wurtzite-phase InAs nanowires, using controlled droplet displacement followed by resumed growth. By confining the droplet to the nanowire sidewall using zincblende inclusions as barriers, epitaxial growth of horizontal branches from existing nanowires is demonstrated. This is done by tailoring droplet wetting of the nanowire and using identical conditions for the nanowire “stem” and branch growth. This work demonstrates the importance of the droplet dynamics and wetting stability, along with the benefits of crystallographic control, for understanding the growth along different directions. Controlled branched growth is one way to achieve designed nanowire networks.

Growth of III-V semiconductor nanowires and their heterostructures

In this paper, we present a review about recent progress on the growth of III-V semiconductor homo- and heterostructured nanowires. We will first deliver a general discussion on the crystal structure and the conventional growth mechanism of one dimensional nanowires. Then we provide a review about most widely used growth techniques, sample preparation and the cutting edge characterization techniques including advanced electron microscopy, in situ electron diffraction, micro-Raman spectroscopy, and atom probe tomography. In the end, the growth of different heteostructured III-V semiconductor nanowires will be reviewed. We will focus on the morphology dependence, temperature influence, and III/V flux ratio dependent growth. The perspective and an outlook of this field is discussed in order to foresee the future of the fundamental research and application of these one dimensional nanostructures.

Vapour-phase growth of III-V semiconductor nanowires in situ in the TEM

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

VLS Growth of III-V Semiconductor Nanowires on Graphene Layers

ABSTRACTGaP, GaAs, and InP nanowires were grown on graphitic layers by the vapor-liquid-solid method in a metalorganic vapor phase epitaxy chamber. On graphene/SiC(0001), Au particles as catalyst were formed at the steps by controlling the Au deposition rate and the annealing temperature in a low-energy electron microscopy system. GaP nanowires were grown on this substrate, and it was found that vertical nanowires were formed at the steps of the surface. We also performed GaP, GaAs, and InP nanowire growth on graphite substrates. Free-standing nanowires were obtained for all three materials, although they were vertically, diagonally, and laterally-oriented at the same time. The results suggested that the growth at the steps is the key to growing nanowires vertically on graphene surface.