Fast vapor growth of cadmium telluride single crystals

Abstract

Cadmium telluride single crystals were grown at growth rates of 35 mm per day by the physical vapor transport (PVT) method under high temperature gradient conditions. This is believed to be the highest PVT growth rate of CdTe reported to date. Lamellar twins are the only ones present in the CdTe crystals grown under optimal conditions in this work. At growth rates up to 15 mm per day, the crystals have a dislocation density of ∼10⁴ cm⁻². The etch pit density increases to ∼10⁵ cm⁻² with an increase of the growth rate up to 35 mm per day. Based on a uniform thermal field and high interface stability, which are established by large temperature gradients up to 40°C/cm at the growth interface, spurious nucleation and lateral twins were effectively eliminated, and the density of the lamellar twins remained low at crystal growth rates up to 35 mm per day. The major contributions of the high temperature gradients to the single crystalline growth and the apparent origin of polycrystalline grains are also discussed in this paper.