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Placement of Si (yellow, light) and Ge (blue, dark) atoms in (a) fully ordered (Si–Ge and Si–Si bonds) and (b) partially ordered (Si–Ge, Ge–Ge, and Si–Si bonds) eight-atom supercells.
Energy levels in Si dot embedded in ordered buffer. Energies are referenced to the valence band point. Inserts show spatial distribution of wave functions for the lowest levels.
Valley splitting for the lowest orbital level as a function of the dot size for ordered (black), partially ordered (red), and disordered (blue) buffer. Bars indicate standard deviation for each point. An example of valley splitting distribution for 100 realizations of buffer disorder is shown in the histogram for ; blue curve is the Gaussian fit.
Valley splitting for the lowest orbital level of Si dot as a function of the dot thickness in monolayers. is calculated using . Thin line connects points with 1 ML step, thick lines connect points for even (open dots) and odd (solid dots) monolayers. Bars indicate standard deviations for different disorder realizations. In the inset for ordered and disordered buffers are plotted. Dashed line is obtained analytically for the 2D case. Stars show percent of the wave function penetrating into the buffer in -direction (right scale).
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