Deep levels which were related to defects, in high-resistivity un-doped liquid-encapsulated Czochralski, were generated during growth or by low-fluence proton irradiation to between 2.6 x 1010 and 1.3 x 1011/cm2. They were investigated by means of photo-induced current transient spectroscopy. In order to compare effects which arose from defects in the bulk to those which arose from defects at the surface, sandwich Schottky diodes and planar samples with two ohmic contacts on the front face were studied. It was found that 5 main traps could be detected. It was shown that, in addition to the apparent activation energies, the nature of the carrier traps could also be determined. Irradiation with protons resulted in the creation of a new electron trap at almost 0.72eV below the conduction band. It was also shown that appreciable changes in the photo-induced current transient spectra could occur upon changing the wavelength of the exciting light.

D.Seghier: Journal of Physics D, 1996, 29[12], 3101-5