TIME-RESOLVED PHOTOLUMINESCENCE MEASUREMENTS IN SPARK-PROCESSED BLUE AND GREEN EMITTING SILICON

Time-resolved photoluminescence (PL) measurements on spark-processed S i (sp-Si) are compared with those on dry-oxidized porous Si (p-Si). Bo th types of substances yield non-exponential decay times in the nanose cond region which are essentially independent of the detection wavelen gth. However, subtle differences between photoluminescing sp-Si and ox idized p-Si exist. Specifically, blue/violet emitting sp-Si has a peak wavelength near 410nm (3 eV) under steady state conditions whereas ox idized p-Si luminesces with a maximum centred around 460-480 nm (2.7-2 .58 eV). Further differences include the peak structures in the PL spe ctra, the decay dynamics, and certain features in the lifetime distrib ution. It is concluded from the data that sp-Si and p-Si derive their PL from somewhat different mechanisms. Moreover, differences in decay times between SiO2 and sp-Si suggest that silica does not seem to be t he major cause for PL in sp-Si.