Microstructure of spark-processed blue luminescent CdTe, GaSb, and InSb

Low frequency spark-discharges were applied to single crystalline wafers of CdTe, GaSb, and InSb. The samples were characterized by photoluminescence spectroscopy at room temperature using an excitation wavelength of 325 nm. The morphology was determined by optical, scanning electron and atomic force microscopy. In spite of the morphological differences occurring at micrometric scales, the spectral regions in which luminescence is observed are almost the same. The origin of the blue luminescence could be an opening of the bandgap due to a quantum confinement effect. In order to estimate the size of the confinement regions, the effective mass approximation model was used. The obtained values of the size of these confinement regions (d) were: for CdTe, d = 30 Angstrom, for GaSb, d = 50 Angstrom and for InSb, d = 25 Angstrom.