Different growth regimes in InP nanowire growth mediated by Ag nanoparticles

Abstract

We report on the existence of two different regimes in one-step Ag-seeded InP nanowire growth. The vapor-liquid-solid-mechanism is present at larger In precursor flows and temperatures, ∼500 °C, yielding high aspect ratio and pure wurtzite InP nanowires with a semi-spherical metal particle at the thin apex. Periodic diameter oscillations can be achieved under extreme In supersaturations at this temperature range, showing the presence of a liquid catalyst. However, under lower temperatures and In precursor flows, large diameter InP nanowires with mixed wurtzite/zincblende segments are obtained, similarly to In-assisted growth. Chemical composition analysis suggest that In-rich droplet formation is catalyzed at the substrate surface via Ag nanoparticles; this process might be facilitated by the sulfur contamination detected in these nanoparticles. Furthermore, part of the original Ag nanoparticle remains solid and is embedded inside the actual catalyst, providing an in situ method to switch growth mechanisms upon changing In precursor flow. Nevertheless, our Ag-seeded InP nanowires exhibit overall optical emission spectra consistent with the observed structural properties and similar to Au-catalyzed InP nanowires. We thus show that Ag nanoparticles may be a suitable replacement for Au in InP nanowire growth.

Understanding GaAs Nanowire Growth in the Ag–Au Seed Materials System

“…We note that μ Ga does change with V/III ratio and this could be used to affect the VSS to VLS transition. This is in line a recent report on Ag-seeded growth of InP, where a VSS to VLS transition could be observed by increasing the temperature and In flow . However, there is a limit on the V/III ratio, as too low AsH 3 flows may lead to the formation of Ga droplets and onset of self-catalyzed nanowire growth …”

“…This is in line a recent report on Ag-seeded growth of InP, where a VSS to VLS transition could be observed by increasing the temperature and In flow. 32 However, there is a limit on the V/III ratio, as too low AsH 3 flows may lead to the formation of Ga droplets and onset of self-catalyzed nanowire growth. 70 In essence these calculations give an underlying explanation for the lower Ga-concentrations in the Ag seeds and, thus, why the nanowire growth stays in the VSS growth regime.…”

“…However, a deep understanding of the effects of the seed materials on the growth is required to be able to adjust them purposefully. Ag is more similar to Au in bulk properties than any other metal and it is among the most studied alternative seed materials for III–V nanowire growth. ,− However, all of these studies report nanowire growth behavior that is very different than for Au and there remains a significant gap in the understanding of how the seed material determines the nanowire properties.…”

Microscopic Understanding of the Growth and Structural Evolution of Narrow Bandgap III–V Nanostructures

“…Au catalysts have frequently used in the epitaxial growth of GaAs ( Figure 2 a), [ 24 ] GaSb ( Figure 2 b) [ 25 ] and InAs NWs. Except for the frequently used Au NPs, Pt, Ag and Cu have also been used as seed particles for the epitaxy growth of III–V NWs [ 26 , 27 , 28 , 29 ]. The physical properties of III–V NWs are closely related with their growth orientation, phases and diameters; thus, the controlled synthesis of III–V NWs is quite important.…”

Planar vs Non-Planar Orientation in AuAg-Catalyzed InP Nanowire Growth

“…19−22 For InP nanowires in particular, Au, Ag, and Pd, along with In itself, have been identified as catalysts that yield high-quality nanowires. 19,23,24 While significant efforts have been made to integrate vertical nanowires into the current processing technologies, 25 the growth of planar nanowires has garnered attention due to their straightforward integration capabilities. 26−34 For GaAs nanowires, a relationship between the substrate orientation and the nanowire growth direction was observed; 28 further studies allowed lateral p−n junctions in this configuration.…”