OBSERVATION OF E-2 PEAK SPLITTING OF SI-GE SHORT-PERIOD SUPERLATTICE

We report spectroscopic ellipsometry studies on (Si)(2)(Ge)(12), (Si)( 6)(Ge)(2), and (Si)(12)(Ge)(2) short period superlattices whose optica l response has not been studied yet. By using multilayer calculation w e could isolate the dielectric response of superlattice layers. It is well known that E-2-transition has several contributions from differen t points in Brillouin Zone. However, previous ellipsometric studies ha ve not presented spectra with split E-2-peak so far. In this work, we report the observation of clear splittings of E-2-peak in (Si)(m)(Ge)( n) superlattices, contrary to the previous report that the splitting w as not observed for small m and n values.