LUMINESCENCE OF SPARK-PROCESSED MATERIALS

High-frequency spark discharges were applied to the following semicond ucting and semi-metallic materials: Sb, Bi, Sn, As, Ge, GaAs, Si, Te a nd Se. The spark-processed (sp) samples were characterized by photolum inescence (PL) measurements using an excitation wavelength of 325 nm. With the exception of Se, PL signals in the visible region were obtain ed for all of the above-specified materials. The strongest and most st able PL was found in sp-Si and sp-Ge layers with peak wavelengths cent red at 525 and 416 nm. respectively. The estimated increase of the ban dgap energy due to the formation of nanocrystals was calculated using the effective mass approximation. The results are in accordance with t he PL data. The particle sizes are expected to range from 3 to 8 nm. T he findings support the quantum confinement model.