Modified Bridgman growth of CdTe crystals

With the aim of improving the structural perfection and reduce the Te particle concentration in CdTe crystals, a modified Bridgman method with artificial seeding has been developed. It allows the adjustment of different degrees of superheating of the melt before the growth process is started. For this purpose, a turning furnace was designed and employed. Crystals with 20 mm diameter and 100 mm length were grown using different superheating temperatures and then structurally, optically and electrically characterized. A moderate improvement of the structural quality is obtained, when the CdTe melt is superheated 110 K above the melting point (1365 K) for 24 h before the crystal growth process. An effective reduction of the Te particle concentration has been observed in the as-grown crystals. The results are correlated to the highly associated melt structure that dissociates after superheating of 110 K by the formation of mono-dimensional species. The technical growth modification could be an interesting alternative to produce CdTe crystals with improved quality for detector devices.