Statistics of three-dimensional island growth for a reactive interface: Ni/GaAs(110)

Abstract

Island size distributions and number densities have been derived from scanning tunneling microscopy images of Ni deposited on cleaved GaAs͑110͒ at room temperature and above. For submonolayer coverages, this system forms three-dimensional ͑3D͒ reacted islands with the degree of reaction dependent upon the growth temperature. The form of the measured island size distributions is consistent with nucleation of the islands via an adatom-substrate exchange process-i.e., the critical island size is zero. For large island sizes and room-temperature growth, plots of the area-normalized island size distribution versus the scaled variable s/s av ͑with s av the average island size͒ all fall on a common curve. In contrast to expectations for exchange nucleation, the total number density of islands is found to decrease with temperature. A rate equation model has been extended to account for the growth of 3D islands and to incorporate the possibility of first-order rate processes ͑rate proportional to monomer density͒. Model results show that the observed island size distribution can be produced by any first-order process, and suggest characteristics of the actual growth kinetics relevant to this ternary system. ͓S0163-1829͑96͒03235-3͔

Interplay of stress and magnetic properties in epitaxial MnAs films

“…The analysis of the data suggests the following scenario for the MnAs layer formation. The adatom supersaturation on the surface is so high that the stable nucleus is only a few atoms, in analogy with submonolayer growth on semiconductor [78][79][80][81] and metal surfaces [82][83][84][85][86][87]. Whereas in the early MnAs growth stages by RHEED only a diffuse background intensity is found, irregularly shaped islands are observed by STM, as shown for a coverage of 0.4 ML in figure 3(b).…”

Scanning Tunneling Microscopy Determination of Single Nanocrystal Core Sizes via Correlation with Mass Spectrometry

“…16 Samples were imaged under ultrahigh vacuum conditions in a room-temperature STM system. 23 Electrochemically etched tungsten tips were cleaned by electron-bombardment heating prior to use. Samples were not treated or cleaned in any way once they were under vacuum.…”