S. Hitomi et al., PHOTOLUMINESCENCE AND RAMAN-SPECTRA OF SI SI1-XGEX STRAINED SUPERLATTICES UNDER HIGH-PRESSURE/, Journal of physics and chemistry of solids, 56(3-4), 1995, pp. 393-396
We investigated photoluminescence spectra in strained Si/Si1-xGex supe
rlattices as a function of pressure. The double-crystal X-ray diffract
ion patterns prove that there is tetragonal lattice distortion in the
alloy layer grown epitaxially on a Si substrate. The effects of lattic
e distortion and alloy composition are confirmed by Raman spectra. The
excitonic photoluminescence spectra are assigned to the free-excitoni
c no-phonon transitions and their phonon replicas. The photoluminescen
ce peaks show negative pressure dependencies of -15.0 to -16.0 meV/GPa
. This result means that the conduction-band minimum is at the X point
as in bulk Si.