Dependence of InGaP nanowire morphology and structure on molecular beam epitaxy growth conditions

Abstract

InGaP nanowires (NWs) were grown by the Au-assisted method in a gas source molecular beam epitaxy system. The dependence of InGaP composition, morphology and stacking fault density was studied with respect to group III and V impingement rate and size of the Au particle. Compositional analysis showed that the NWs had an In-rich core and a Ga-rich shell structure. The In incorporation within the NW became limited as the Au seed particle size diminished or the group III and V flux decreased. The NWs had wurtzite (WZ) crystal structure with zinc blende (ZB) segments (stacking faults). The density of the stacking faults decreased as the group III flux decreased and the group V flux increased.

Single GaInP nanowire p-i-n junctions near the direct to indirect bandgap crossover point

“…26 Note, however, that we did not observe radial growth of a Ga-rich shell in TEM, 13 as previously found in MBE-grown GaInP. 10 At room temperature, the carriers recombine before diffusing to these low-bandgap regions, thereby explaining the observed single peak.…”

“…7 GaInP shells grown on GaAs NW cores have been used for NW-based LEDs on silicon, 8 while others have investigated strained GaInP NW shells 9,34 and molecular beam epitaxy (MBE)-grown GaInP NWs. 10 Theoretically, GaInP can reach a direct band gap of up to about 2.2 eV at room temperature, 11 but at the corresponding composition there is no suitable substrate for thin-film growth. Axial NW heterostructures, however, can be grown with large lattice mismatch since the strain can be relaxed vertically, and here we demonstrate devices with a bandgap close to the theoretical limit.…”

Facilitating growth of InAs–InP core–shell nanowires through the introduction of Al

“…Although the growth mechanisms responsible for this effect are not fully understood, the adatom diffusion appeared to be significantly reduced during shell growth in the presence of Al. Based on prior studies [37,38], the adatom diffusion length of In, Ga, and Al are believed to consecutively decrease. Al adatoms, in particular, are known to have a relatively short diffusion length, which has been used to create AlGaAs shells on GaAs cores [38,39].…”

Modelling of InGaP nanowires morphology and composition on molecular beam epitaxy growth conditions

“…12 In the VLS process, a metal catalyst (typically Au) acts as a collecting agent for reactants resulting in siteselective growth of NWs. Both metalorganic vapor phase epitaxy (MOVPE) 13 and molecular beam epitaxy (MBE), 14,20 as well as other techniques 12,15 have been used for the growth of NWs.…”

“…We have previously reported on the influence of MBE growth conditions on morphology, composition, and crystal structure of InGaP NWs. 20 In this paper, we develop a detailed analytical model for the evolution of NWs depending on MBE growth parameters.…”