Coalescence behaviour of gold particles vacuum evaporated onto doped alkali halide substrates

Abstract

A series of gold deposits with equivalent mean thicknesses of 2.1, 3.0, 4.5, 6.0, 9.0 and 12 Å were grown in high vacuum at deposition rates of 0.3 and 0.1 Å s -1 (with continuous or intermittent incident atom fluxes) on doped KBr and NaCl substrates heated to 290, 260 or 170°C. The dependences of the main nucleation and growth parameters (the specific particle density n x , the ratio of the percentages S 100 and S 111 or oriented particles, the surface coverage Z, the mean particle diameter D̄) on the equivalent mean thickness t were determined by electron microscopy and electron diffraction. In order to illustrate the growth coalescence and secondary nucleation processes clearly, histograms of the distribution of gold particles at diameter intervals (normalized to 2 × 10 7 A ̊ 2) were also plotted. The results showed that there is no simple correlation between the extent of coalescence of the mobile particles and the degree of epitaxial orientation.