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.

We present results that provide fundamental insights on how to experimentally tailor the planar defect density and even the crystal structure in III−V metal particle seeded nanowires, where zinc blende is the stable bulk crystal structure. We have grown GaP nanowires with metal-organic vapor phase epitaxy under different conditions: pulsing of the Ga source, and continuous growth with and without In background. The dominant crystal structure of the nanowires is zinc blende, which when grown under continuous conditions has a high density of twin planes perpendicular to the growth direction. Using pulsed growth, we observed that the twin plane separations were much longer than those observed for continuous growth with an In background. On the other hand, during continuous growth, under In-free conditions, a considerable amount of the wurtzite phase forms. We explain the importance of the In background during growth. With classical nucleation modeling we qualitatively relate the density of planar defects in a nanowire to the growth conditions. For low supersaturations, we predict a low twin plane density, consistent with our experimental observations of pulsed nanowire growth. In addition, we suggest that under certain conditions, it might be possible to grow wires with almost perfect wurtzite structure.

Recent relationships between Papua New Guinea (PNG), the International Monetary Fund (IMF), and the World Bank have been stormy. At various points in the loan negotiations students rioted, the Prime Minister told the World Bank to 'go to hell', and the World Bank's chief negotiator defected to the PNG side. He was later jailed. The relationship between the Asian Development Bank (ADB) and its South Pacific clients were also sometimes uneasy, and led its Board of Directors to commission a self-assessment (Knapman and Saldhanha 1999). The article compares the use of loan conditions by the International Financial Institutions (IFIs) in Papua New Guinea and six small island states of the South Pacific. In spite of their juridical sovereignty, their small size may make them particularly vulnerable to international pressure (Warrington 1998:101). It is part of a wider study of 'institutional transfer ' which sees 'conditionality' as one of the mechanisms by which institutions are borrowed, transplanted or imposed on other countries. Conditionality lies on a continuum that runs from voluntary 'lesson drawing' at one extreme, to direct imposition of a policy on the other (Dolowitz and Marsh 1996, 2000).

We demonstrate that the crystal structure of InAs nanowires can be controlled with nanowire diameter and growth temperature. At small diameters, the nanowires exhibit a wurtzite structure. As the diameter is increased, there is a crossover to the zinc blende structure. The crossover is less sharp at lower growth temperature and the crossover diameter decreases as the growth temperature is increased. We explain these results with classical nucleation theory. The strong diameter dependence is accounted for by including the Gibbs−Thomson effect in the chemical potential.