Abstract
The ion-induced nanoscale pattern formation on a crystalline Ge(001) surface is observed in situ by means of grazing incidence small angle x-ray scattering (GISAXS). Analysis of the GISAXS intensity maps yields the temporal development of geometric parameters characterizing the changing pattern morphology. In comparison with theoretical predictions and with simulations of the patterning process based on a continuum equation we find good agreement for the temporal evolution of the polar facet angle, characteristic length, and surface roughness in the nonlinear regime. To achieve this agreement, we included an additional term in the continuum equation which adjusts the pattern anisotropy.
Highlights
Irradiating a solid surface with low-energy ions can lead to various effects on the nanoscale surface topography [1,2,3], ranging from smoothing [4] to the formation of ripple or dot patterns [5,6] to the self-assembly of faceted and highly regular morphologies [7]
From the perspective of fundamental science, nanoscale pattern formation under ion irradiation is considered an example of complex nonequilibrium dynamics; the observable patterns are the result of the interplay of numerous erosive, ballistic, and diffusive mechanisms on the atomic scale
The in situ grazing incidence small angle x-ray scattering (GISAXS) experiment was conducted at the Integrated In-Situ and Resonant Hard X-ray Studies (ISR) beamline of the NSLS-II synchrotron x-ray source at Brookhaven National Laboratory, employing a custom-made UHV chamber with a base pressure of p0 = 10−6 mbar
Summary
Irradiating a solid surface with low-energy ions can lead to various effects on the nanoscale surface topography [1,2,3], ranging from smoothing [4] to the formation of ripple or dot patterns [5,6] to the self-assembly of faceted and highly regular morphologies [7]. Ion-induced patterning has turned out to occur on a large number of materials and to be widely tunable via external control parameters. It is a highly versatile technique for many applications where large areas of nanostructured surfaces or thin films are required. Both fundamental and applied research may benefit from in situ studies revealing the time-dependent development of the patterning process, yielding further insight into the dominant
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