Effect of Si(111) Surface Modification by Ga Focused Ion Beam at 30 kV on GaAs Nanowire Growth

Abstract

This paper presents the results of experimental studies of the effect of Si(111) surface modification by Ga-focused ion beam (FIB) at 30 kV accelerating voltage on the features of the epitaxial GaAs nanowire (NW) growth processes. We experimentally established the regularities of the Ga ions’ dose effect during surface modification on the structural characteristics of GaAs NW arrays. Depending on the Ga ion dose value, there is one of three modes on the surface for subsequent GaAs NW growth. At low doses, the NW growth is almost completely suppressed. The growth mode of high-density (up to 6.56 µm−2) GaAs NW arrays with a maximum fraction (up to 70%) of nanowires normally oriented to the substrate is realized in the medium ion doses range. A continuous polycrystalline base with a dense array of misoriented short (up to 0.9 µm) and thin (up to 27 nm) GaAs NWs is formed at high doses. We assume that the key role is played by the interaction of the implanted Ga ions with the surface at various process stages and its influence on the surface structure in the modification region and on GaAs NW growth conditions.

Modulation of GaAs nanowire growth by pre-treatment of Si substrate using a Ga focused ion beam

“…The second approach involves FIB treatment of the surface followed by ultra-high vacuum (UHV) annealing of the substrate. This technique operates as follows: during annealing, embedded ions generate metal catalyst droplets (such as Ga or Au) on the surface at the treatment sites, enabling self-catalytic NW growth within precisely defined irradiation areas [10][11][12][13][14][15]. This approach allows for considerable variation in the ion dose and distance between exposure points.…”

“…Particularly, specific parameters of the ion beam treatment make it possible to achieve 100% yield of vertically oriented NWs. By employing this approach, NWs based on various semiconductor materials can be formed, such as GaAs NWs using Ga [15,16] and Au [12,14] ions, Si NWs using Ga ions [17], InAs NWs using Au ions [13], etc. It is also worth noting that substantial suppression of NW growth is observed on surfaces irradiated with an accelerating voltage of 30 kV [10,11].…”

Focused ion beam lithography for position-controlled nanowire growth

“…Alternatively, direct patterning of holes could lead to increased positioning flexibility and a simplified fabrication process. This can be achieved by a focused ion beam (FIB) [25], an approach which has so far been primarily explored in proof-of-principle studies [26][27][28][29][30][31][32][33]. These studies are mostly random area growth, but suggest that single nanowire positioning should be achievable after optimizing patterning conditions.…”