CRUCIAL ROLE OF SI BUFFER LAYER QUALITY IN THE PHOTOLUMINESCENCE EFFICIENCY OF STRAINED SI1-XGEX SI QUANTUM-WELLS/

The crucial role of Si buffer layer quality in strained Si1-xGex/Si qu antum well structures is investigated in terms of quantum efficiency o f luminescence. The close correlation between etch-pit density (EPD) i ncrease and luminescence quenching is presented for the first time. It is shown that strained Si1-xGex/Si quantum wells with a high degree o f luminescence efficiency can be obtained only on a high-quality Si bu ffer layer grown at temperatures higher than 700 degrees C, which give s an EPD lower than 10(6) cm(-2).