Preparation and properties of bulk ZnSe:Cr single crystals

Cr-doped zinc selenide single crystals have been prepared by a two stage process. In the first stage, undoped single crystals were grown by a sublimation traveling heater method (STHM) without seeding. The high quality of the as-grown crystals was confirmed by double crystal X-ray diffraction, which showed the full-width half-maximum (FWHM) of the rocking curves to be less than 20 arcsec on the (2 2 0) diffraction planes of the crystals. Selective chemical etching showed dislocation density of these faces to be less than 5 x 10(4) cm(-2). In the second stage, the ZnSe crystals were Cr-doped by the method of the thermal diffusion from a solid metal source. Cr concentration of 3.3 x 10(19) cm(-3), absorption coefficient of more than 30 cm(-1) at 1750 nm, and passive losses of less than 0.3 cm(-1) at 2500 nm were obtained under optimal technological conditions. (C) 1999 Elsevier Science B.V. All rights reserved.