Near Band-Edge Photoluminescence in Strained and Relaxed Si1-xGex/Si Quantum Wells

Near band-edge photoluminescence was observed from strained and relaxed Si1-xGex/Si quantum wells grown by molecular beam epitaxy and annealed at 850–1100°C. Changes in the photoluminescence line energies were monitored, and the extent of both interdiffusion and relaxation in wells during annealing was calculated. Strain relaxation was observed only in quantum well structures annealed above 950°C. The experimental data confirmed the existence of an abrupt transition between stable and strain-relaxed Si1-xGex/Si quantum well structures, and it was also observed that photoluminescence was sensitive enough to detect the onset of strain relaxation in quantum well structures following rapid thermal annealing.