Preparation and properties of bulk ZnSe : Cr single crystals

Abstract 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 5×10 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 3.3×10 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.