Effect of Au thickness on the evolution of self-assembled Au droplets on GaAs (111)A and (100)

Abstract

In this paper, we report the effect of Au thickness on the self-assembled Au droplets on GaAs (111)A and (100). The evolution of Au droplets on GaAs (111)A and (100) with the increased Au thickness progress in the Volmer-Weber growth mode results in distinctive 3-D islands. Under an identical growth condition, depending on the thickness of Au deposition, the self-assembled Au droplets show different size and density distributions, while the average height is increased by approximately 420% and the diameter is increased by approximately 830%, indicating a preferential lateral expansion. Au droplets show an opposite evolution trend: the increased size along with the decreased density as a function of the Au thickness. Also, the density shifts on the orders of over two magnitude between 4.23 × 1010 and 1.16 × 108 cm−2 over the thickness range tested. At relatively thinner thicknesses below 4 nm, the self-assembled Au droplets sensitively respond to the thickness variation, evidenced by the sharper slopes of dimensions and density plots. The results are systematically analyzed and discussed in terms of atomic force microscopy (AFM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), cross-sectional surface line profiles, and Fourier filter transform (FFT) power spectra.

Au-catalyzed desorption of GaAs oxides

“…Starting from the initial stage with Au on the oxides in figure 6 Though the model is proposed based on experiments using Au particles in their native form it should hold in cases where Au particles are prepared by other means, including the conventional method deposition and annealing, provided the initial Au layer is sufficiently thin (typically a few nm or lower), non conformal (substrate kept at a low temperature during deposition, e.g. 300 °C, to suppress adatom diffusion), and the annealing occurs under or near ultra high vacuum conditions [49,50]. These conditions ensure the dewetted Au take the form closely resemble those of isolated particles.…”

A controlled nucleation and growth of Si nanowires by using a TiN diffusion barrier layer for lithium-ion batteries

“…of the deposited material during Au deposition onto SS304 and TiN substrates. 30 Thus, Au on SS304 and TiN formed nanodots spontaneously, as shown in Figures 1(c) and (e).…”

“…The surface free energy difference between Au and Si (111) is less than 0.3 eV, whereas the difference between Au and Fe or TiN is about 1 eV. The signicant difference in surface free energy among Au, Fe, and TiN induces Volmer-Weber mode of deposition, resulting in dot formation due to unfavorable wetting of the deposited material during Au deposition onto SS304 and TiN substrates 30. Thus, Au on SS304 and TiN formed nanodots spontaneously, as shown in Fig.1(c) and (e).…”

Shape transformation of self-assembled Au nanoparticles by the systematic control of deposition amount on sapphire (0001)

“…Also, the size and density evolution of Au NPs with the incremental variation of deposition amount was studied on GaAs, Si and TiO 2 substrates. [26][27][28][29] Similarly, the Pt NPs on Si and SiO 2 substrates, 30,31 and Ga NPs on GaAs substrate etc. 32 demonstrated the increased dimension as well as decreased density of NPs with the increased deposition amount.…”

“…6 In addition, with respect to the shape and size of Au NPs, the SPR absorption and scattering properties of various sizes of Au nano-spheres, nano shells and nano rods have led to the highly efficient performance of biological applications. 9 Meanwhile, metal NPs have been demonstrated with various shapes such as cubic, 13 triangle, 14 dome, 15 bipyramids, 16 octahedral, 17 nanoprism, 18 and trisoctahedral 19 in numerous growth techniques. It is rarely reported the shape transformation of NPs in physical vapor deposition (PVD) growth technique.…”