BRIDGMAN GROWTH OF HG1-XCDXTE FROM MELT OF CONSTANT COMPOSITION

A modified Bridgman method is applied for the growth of semiconducting alloys Hg1-xCdxTe from the melt. The large separation between the liq uidus and solidus lines in the T-x phase diagram and further non-plana r melt/crystal interface shape cause significant axial and radial grad ients in the composition. In order to reduce these difficulties, the p roposed method - Bridgman growth from melt of constant composition (BG CC) - is based on a demand to simply ensure a melt of constant composi tion near the melt/crystal interface during growth. The missing CdTe i s transported to the phase boundary by diffusion from a suitable sourc e - for example floating solid CdTe. A model of diffusion of CdTe in t he liquidus was verified by a fast cooling of the melt above the growi ng crystal and its composition analysis. In this way the equilibrium s egregation coefficient and solute diffusion coefficient of CdTe were d etermined. As-grown crystals were p-type Hg-vacancy-doped. By an annea ling near-Hg-saturated condition or in a Hg bath, and also by ion beam milling, the n-type material can be prepared. Electrical, optical and photoelectrical properties are briefly discussed.