EFFECTS OF HYDROSTATIC-PRESSURE ON THE PHOTOLUMINESCENCE OF POROUS SILICON

We have measured the room-temperature photoluminescence (PL) of free-standing porous silicon films under hydrostatic pressures up to 60 kbar. The pressure dependence of the PL for two films collected from the same porous silicon wafer is very different, depending on whether the pressure medium used is either helium or the standard 4:1 methanol:ethanol mixture. This result is not compatible with the standard quantum confinement model of the PL in porous silicon, which claims that the PL occurs between the confined electron and hole states in the core silicon region.