Low supersaturation nucleation and “contactless” growth of photorefractive ZnTe crystals

New photorefractive ZnTe crystals have been successfully grown by methods previously applied only for the growth of CdTe single crystals [K. Grasza, J. Crystal Growth 146 (1995) 65]. The main feature of this method lies in the novel procedure of self-seeding in conditions of permanently low supersaturation, growth with no contact between the crystal and ampoule wall, self-purification and improvement of stoichiometry of the source material during growth. Additionally, a new procedure of lowering the optimal growth temperature was applied and an optimal growth rate with stable growth conditions was investigated. The ZnTe crystals had resistivity exceeding 10(8) Omega.cm. Photorefractive characterization was performed using the two-beam mixing technique, and the photorefractive gain in the range 0.63-1.5 mu m was measured.