PHOTOREFLECTANCE OF SINGLE BURIED SI1-XGEX EPILAYERS (0.12-LESS-THAN-X-LESS-THAN-0.24)

Photoreflectance spectra have been obtained from single strained Si1-xGex epilayers (0.12 < x < 0.24) buried under a silicon cap. Despite dramatic changes in the shape of photoreflectance spectra obtained at different positions on a sample wafer, which are explained in terms of a strong interference effect as the Si cap thickness varied, spectra were fitted adequately using three Lorentzian oscillators. Critical point transition energies calculated in this way were consistent with E(1) and E(1)+Delta(1) in Si1-xGex and E(0)' in silicon and allowed for determination of composition to within x +/- 1.5%. (C) 1995 American Institute of Physics.