Electrical, photoelectrical, luminescent characteristics and the spectra of deep levels are compared for undoped semi-insulating SI-GaAs crystals grown by vertical gradient freeze (VGF) and liquid encapsulated Czochralski (LEC) techniques. It is shown that generally the reverse current of the Schottky diodes prepared on VGF material is considerably lower than for the LEC material which could be a serious advantage for use in radiation detectors. At the same time it is demonstrated that such parameters as photosensitivity and bandedge luminescence efficiency are to a greater extent dependent on the type of the ingots annealing procedure setting up the deep levels spectra in the material than on dislocation density. (C) 2003 Elsevier Ltd. All rights reserved.