LUMINESCENCE STUDIES OF CONFINED EXCITONS IN PSEUDOMORPHIC SI/SIGE QUANTUM-WELLS GROWN BY SOLID SOURCE MOLECULAR-BEAM EPITAXY

Band gap luminescence from pseudomorphic Si/Si1-xGex/Si quantum wells grown by solid source molecular beam epitaxy is studied for a composition range from x = 0.14 to x = 0.28 and well widths from 1.6 to 6.4 nm. All peak energies are in good agreement with recent results on wide wells and are close to theoretical calculations. With decreasing well width, a systematic decrease of the intensity of the no phonon transition with respect to its phonon replica is observed. For the highest Ge contents, confinement energies of more than 130 meV are evaluated. Realistic Ge profiles including segregation effects of Ge during growth are used for calculating confinement energies. The results demonstrate the importance of segregation for the used growth parameters.