A new approach to crystal growth of Hg 1 _ ~ Cd ~ Teby the travelling heater method ( THM )

Crystal growth by the travelling heater method (THM) is reported using a source material preparation process that is different from all methods used before. Non-stoichiometric (Hg,Cd)Te melts were homogenized and quenched to prevent macroscopic segregation effects. Inclusions of excess Te were removed during a first THM pass, resulting in stoichiometric solid alloys with a shift of the mole fraction towards higher CdTe contents. The amount of the shift, dependent on the Te excess and on the equilibrium temperature of the first THM run, was calculated and taken into account in the preparation of x 0.22 and x = 0.30 Hg1 ~Cd~Te single crystals. Source material ingots, as well as THM single crystals, were characterized with special emphasis of the compositional homogeneity. Radial as well as axial homogeneity are comparable with the best results on THM crystals reported so far. The described method can be used in growing all materials for which THM is possible. However, quantitative calculation requires the exact knowledge of the particular ternary phase diagram.