Fabrication of strain-balanced Si/Si1-xGex multiple quantum wells on Si1-yGey virtual substrates and their optical properties

Strain-balanced Si/SiGe multiple quantum wells (MQWs), which are designed t o overcome the limitation of the number of wells coming from the strain acc umulation, were fabricated, and their optical properties were investigated. X-ray diffraction spectra and cross-sectional transmission-electron-micros cope images showed a high-crystalline quality of samples and excellent unif ormity of the well width. Well-resolved no-phonon and TO-phonon-assisted tr ansitions from strain-balanced MQWs were observed by low-temperature photol uminescence spectroscopy, and both their temperature and excitation power d ependence showed blueshifts due to the delocalization of excitons, the band bending, and/or the band-filling effect. (C) 2001 American Institute of Ph ysics.