In situ analysis of catalyst composition during gold catalyzed GaAs nanowire growth

Abstract

Semiconductor nanowires offer the opportunity to incorporate novel structures and functionality into electronic and optoelectronic devices. A clear understanding of the nanowire growth mechanism is essential for well-controlled growth of structures with desired properties, but the understanding is currently limited by a lack of empirical measurements of important parameters during growth, such as catalyst particle composition. However, this is difficult to accurately determine by investigating post-growth. We report direct measurement of the catalyst composition of individual gold seeded GaAs nanowires inside an electron microscope as they grow. The Ga content in the catalyst during growth increased with both temperature and Ga precursor flux. A direct comparison of the calculated phase diagrams of the Au-Ga-As ternary system to the measured catalyst composition not only lets us estimate the As content in the catalyst but also indicates the relevance of phase diagrams to understanding nanowire growth.

One-Dimensional (1D) Nanostructured Materials for Energy Applications

“…Unlike top-down techniques, the “bottom-up” approach is based on molecular recognition and chemical self-assembly of molecules, which allows obtaining structures with sizes that can vary from a few nanometers to several microns. This approach, in turn, includes different methodologies, among which it is worth mentioning vapor-phase growth [ 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ], liquid-phase growth [ 51 , 52 ], template-assisted etching [ 53 , 54 , 55 , 56 , 57 ], and electrospinning [ 58 , 59 , 60 , 61 , 62 ].…”

Vapor–solid–solid growth dynamics in GaAs nanowires

“…Further details of the experimental setup can be found in previous publications. 42,54 The layer growth dynamics is recorded as videos made up of a series of TEM images. The growth of each layer is identified as a dynamic change in the contrast at the interface.…”

“…The first two layers that nucleated after the catalyst solidified had shorter incubation time compared to the later layers (Figure 2 a and Supporting Information Figure S2). This can be attributed to a transient effect, as the particle initially has a higher supersaturation due to excess Ga just after solidification (according to the phase diagram 42 Ga solubility in the solid phase is lower than the Ga concentration of liquid Au-Ga). Since the layer completion is expected to be limited by As availability 40 (due to the low solubility of As in the Au-Ga system 36,[42][43][44][45][46] ), the excess Ga is not expected to influence the layer completion time.…”

Optical property and lasing of GaAs-based nanowires

“…Kim and co-workers [47] grew nanoneedles in the pure WZ phase on top of NWs by controlling the V:III ratio and proved that the formation of WZ phase nanoneedles is related to the droplet contact angle. In 2019, Maliakkal and co-workers [48] used an in situ electron microscope and X-ray energy dispersive spectroscopy to measure the catalyst composition during NW growth. They studied the growth of Au-seeded GaAs NWs and found that the Ga content in the catalyst during growth increased with both temperature and Ga precursor flux.…”