RADIATIVE RECOMBINATION IN NEAR-SURFACE STRAINED SI1-XGEX/SI QUANTUM-WELLS

Influence of the surface on the radiative recombination is studied in near-surface (NS) strained Si1-xGex/Si quantum wells (QWs). The luminescence intensity of NSQWs is clearly diminished as the Si cap thickness decreases due to carrier capture to the surface. However, the luminescence diminution discloses a saturable behavior with increasing excitation density. Time-resolved measurements reveal selective electron capture to surface traps as being the controlling process in the luminescence attenuation, and there is no signature of quantum mechanical hole tunneling to the surface. Results of potential-biased luminescence lend further support to the electron-controlled picture of the luminescence attenuation in Si-based near-surface geometry. (C) 1995 American Institute of Physics