Control of III–V nanowire crystal structure by growth parameter tuning

Abstract

In this work we investigate the variation of the crystal structure of gold-seeded III-V nanowires with growth parameters, in order to gain a cohesive understanding of these effects. We investigate six III-V materials: GaAs, InAs, GaP, InP, GaSb and InSb, over a variation of growth conditions. All six of these materials exhibit a cubic zinc blende structure in bulk, but twin planes and stacking faults, as well as a hexagonal wurtzite structure, are commonly observed in nanowires. Parameters which may affect the crystal structure include growth temperature and pressure, precursor molar fraction and V/III ratio, nanowire diameter and surface density, and impurity atoms. We will focus on temperature, precursor molar fraction and V/III ratio. Our observations are compared to previous reports in the literature of the III-V nanowire crystal structure, and interpreted in terms of existing models. We propose that changes in the crystal structure with growth parameters are directly related to changes in the stable side facets.

Gold-free GaAs/GaAsSb heterostructure nanowires grown on silicon

“…The control of phase purity in III-V NWs is a very active research area, as most of these naturally show polytypism. 12 We note that our results are in perfect agreement with previously studied gold-seeded GaSb or GaAsSb NWs, [13][14][15] although the growth mechanism, growth conditions, and substrate used are completely different. In view of these studies and of the present work, it is clear that this effect should be linked to the presence of antimony, independent of the nature of the seed particle droplet, and could be linked to its well known surfactant properties.…”

Thermal conductivity of indium arsenide nanowires with wurtzite and zinc blende phases

“…The other two ZB phase NWs were also found to be along the 111 direction, which is consistent with the observations of previous work on as-grown ZB phase InAs NWs. 34 No twins or stacking faults were observed within the NW regions imaged using TEM for either the ZB or WZ NWs. For the ZB NWs, the presence of a significant number of defects would be observable even in SEM images as their presence would change the cross section due to threefold symmetry.…”

“…The growth directions of the other WZ phase NWs were also found to be along the 0001 direction, consistent with previous observations of as-grown WZ phase InAs NWs. 6,34 Figure 2 is the collection of the SEM and TEM images of the ZB phase NW2. Figure 2(a) is the tilted side-view SEM image of the as-grown ZB phase InAs NW arrays showing their tapered shape, while the inset is a top-down SEM image revealing the triangular cross section of the NWs grown from a hexagonal base.…”

Raman spectroscopy of GaP/GaNP core/shell nanowires

“…18 Growth of NWs is often accompanied by polytypism and formation of various point and planar defects, such as rotational twinning planes and stacking faults, which can affect functionality of electronic and photonic devices based on NWs. 19,20 An effective technique that allows non-destructive characterization of electronic and structural properties of nanoscale materials is micro-Raman spectroscopy. This technique has been applied to several III-V NW systems [19][20][21][22][23][24][25][26][27] and provided important information regarding crystalline structure, such as presence of staking disorder and formation of alternating zinc-blende (ZB)/wurtzite (WZ) (ZB/WZ) polytypes, strain as well as diameter modulations.…”