Phase Selection in Self-catalyzed GaAs Nanowires

Abstract

Crystal phase switching between the zincblende and wurtzite structures in III-V nanowires is crucial from the fundamental viewpoint as well as for electronic and photonic applications of crystal phase heterostructures. Here, the results of in situ monitoring of self-catalyzed vapor-liquid-solid growth of GaAs nanowires by molecular beam epitaxy inside a transmission electron microscope is presented. It is demonstrated that the occurrence of the zincblende or wurtzite phase in self-catalyzed nanowires is determined by the sole parameter, the droplet contact angle, which can be finely tuned

Growth of Self-Catalyzed InAs/InSb Axial Heterostructured Nanowires: Experiment and Theory

“…Inside this range, NWs grow with vertical sidewalls, while they taper at the small or inverse-taper at the large stable contact angle. Similar behavior is observed for self-catalyzed GaP NWs, with the vertical growth region In situ [31] and ex-situ [33] growth studies of self-catalyzed GaAs NWs show the bistability of the Ga droplet angle, with the two stable angles around 90 • and 130 • . Inside this range, NWs grow with vertical sidewalls, while they taper at the small or inverse-taper at the large stable contact angle.…”

“…In situ [31] and ex-situ [33] growth studies of self-catalyzed GaAs NWs show the bistability of the Ga droplet angle, with the two stable angles around 90° and 130°. Inside this range, NWs grow with vertical sidewalls, while they taper at the small or inverse-taper at the large stable contact angle.…”

“…Assuming spherical cap shape of the NP resting on the NW top facet, the contact angle β can be obtained using the known expression tan(β/2) = H/R d [30]. This is a standard method of measuring the contact angle [31]. In order to verify that the droplet geometrical parameters measured ex-situ are representative of the actual droplet shape during growth, we carried out some cooling experiments with and without TDMASb flux (see the Supplementary Material for the details).…”

Effect of Arsenic Depletion on the Silicon Doping of Vapor–Liquid–Solid GaAs Nanowires

“…Due to a small size of a catalyst particle, its group V content drops very substantially in each monolayer (ML) formation cycle and requires the equivalent refill from vapor. [5,7,8] This leads to oscillations of chemical potential of the liquid phase which manifests in the so-called nucleation antibunching, [5] periodically changing morphology of the growth interface, [8][9][10][11] sub-Poissonian nucleation statistics in individual NWs [12] and narrowing effect on the length distributions within the NW ensembles. [13,14] For very low group V concentrations, the fractional ML can even stop growing and then progress much slower at the rate of refill.…”

“…[13,14] For very low group V concentrations, the fractional ML can even stop growing and then progress much slower at the rate of refill. [10,11,15] Electronic and optoelectronic applications of III-V NWs require their controllable doping. Silicon, which is a standard n-type dopant for planar GaAs layers in molecular beam epitaxy (MBE), often becomes p-type dopant in VLS GaAs NWs.…”