TEM cross-sections of the film D deposited at RT (see Table I), depicted in various magnifications.
2D GISAXS maps (upper row) of the films prepared at different conditions, and their simulations (bottom row) obtained by using of gaslike correlation model. The parameters used for the simulation of the maps in the bottom row are obtained by fitting the experimental data and they are summarized in Table II.
The QD parameters, obtained from the GISAXS measurements. (a) Size distributions of the QDs. The distribution obtained for films deposited at are denoted by dashed lines. The inset shows the dependence of the standard deviation of the size distribution on the ratio . (b) Average sizes of the QDs obtained for different films. (c) The density of the QDs in the matrix.
Diffraction patterns of samples A–F, the curves are shifted vertically for clarity. The intensity scale is linear. The dashed lines denote the positions of the diffraction peaks of bulk Ge, the dash-dot line denotes substrate Si (002) diffraction. From the positions of the peaks we determined the concentration of Si in QDs.
(a) First order Raman spectra of the studied samples. The intensity scale is linear. (b) Evolution of the Raman frequencies as a function of the Si content .
The deposition parameters of the investigated films: is the Ar pressure, is the discharge power, Ge:Si denotes the ratio of the surfaces of the Ge and Si targets, is the deposition temperature, is the annealing temperature, and is the annealing time.
Structural parameters of the QDs obtained in the investigated films: and are the values of the mean QD radius determined from GISAXS and XRD, respectively, is the rms dispersion of the radius , is density of the QDs in the matrix, is mean distance between the QDs, is Si fraction in the SiGe lattice of the QDs, is the depletion radius, and is the ratio of the mean distance of the QDs and their depletion radius. All parameters are obtained from GISAXS measurements except and , which are obtained from XRD measurements.
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