| During the early stages of thin film growth in many thin film-substrate systems, adsorbate atoms form discrete three-dimensional islands, typically 10 A to 150 A in size. In order to study these islands, surface sensitive small angle x-ray scattering has been done for the first time by using a grazing incidence geometry (GISAXS). In this method, the substrate is aligned for total external reflection and the islands produce small angle scattering from the refracted beam crossing the substrate surface.; The motivation for developing the GISAXS technique is the advantages GISAXS offers. First, because GISAXS works in reflection, there are no substrate thickness restrictions. Second, there is no sample conductivity requirement. Third, there are no x-ray beam induced sample changes. Finally, the x-ray beam samples all of the islands in the beam path simultaneously.; In order to examine thin films in situ with GISAXS, an ultra-high vacuum chamber has been built which can be attached to a rotating anode or synchrotron x-ray source. This chamber is equipped with a pair of beryllium windows, a metal evaporator, a sample heater, and a precision rotary sample holder feedthrough.; The GISAXS technique was applied to a model system of gold islands on glass substrates. The glass provides high reflectivity and gold provides strong atomic number contrast. For as-deposited films from 5 A to 15 A in average thickness, average island sizes, heights, and preferred island spacings, and the island surface roughness were determined. From the results of low temperature ({dollar}<{dollar}375{dollar}spcirc{dollar}K) post-deposition annealing experiments, a model was developed which explains the observed slow time-dependence of post-deposition island growth in terms of overlapping diffusion fields and mass transfer by island mobility. The activation energy for this process was determined to be 0.49 eV. These GISAXS results were supplemented with transmission electron micrographs of and grazing incidence wide angle x-ray diffraction from representative gold island films.; Finally, island sizes were determined for indium arsenide films on silicon substrates in order to demonstrate the applicability of GISAXS to a non-ideal system. |
