GROWTH AND PHOTOLUMINESCENCE CHARACTERIZATION OF PSEUDOMORPHIC SIGE SINGLE QUANTUM-WELLS

We report on MBE growth and photoluminescence characterization of sing le Si1-xGex quantum wells grown pseudomorphically on Si(100) substrate s. Growth temperature T(G), Ge content x, and quantum well thickness L (z) were varied in a systematic study. x and L(z) were determined by 5 -crystal X-ray rocking analyses. For all growth temperatures studied ( 350 less-than-or-equal-to T(E) less-than-or-equal-to 750-degrees-C) we find SiGe bandedge luminescence consisting of a no-phonon (NP) line a nd four well-resolved phonon replicas. In most samples, only the free exciton but no bound exciton appeared in the spectra, which is indicat ive of a low background impurity level. Line widths down to 2.9 meV fo r the NP line were observed. The bandedge luminescence could be follow ed down to excitation power densities as low as 0.1 mW/cm2. The broad luminescence band located about 150 meV below the SiGe bandgap, which has been reported as a typical feature of MBE grown material, is virtu ally absent in our samples independent of the growth temperatures empl oyed.