Band-edge exciton luminescence from Si/strained Si1−xGex/Si structures

Well-resolved band-edge exciton photoluminescence has been observed in strained Si1−xGex layers grown on Si(100) by rapid thermal chemical vapor deposition. The luminescence is due to shallow-impurity bound excitons at low temperatures (under 20 K) and is an excellent probe of quantum confinement effects in narrow quantum wells. At higher temperatures, the luminescence is due to free excitons or electron hole plasmas, depending on the pump power. Experiments with single and multiple quantum well structures indicate that most of the Si1−xGex luminescence is from carriers which were generated in the silicon substrate and subsequently were trapped in the quantum wells.