BASIC PROBLEMS OF VERTICAL BRIDGMAN GROWTH OF CDTE

Many efforts have been made to grow CdTe bulk crystals with a low defect content but improvements are limited. The best ingots with large extended single-crystal regions can be grown by the vertical Bridgman method. However, fundamental studies about the CdTe growth peculiarities are absent. Our investigations are concentrated on die following problems: (i) the influence of the melt structure, from which an associated state is assumed, on the crystalline quality, (ii) the composition instability in conventional ampoules, (iii) the segregation behaviour of the excess component (normally tellurium), (iv) the axial distribution of inclusions and precipitations, (v) the mass transport in modified ampoules with an additional cadmium source, (vi) the correlation between the vacancy and impurity segregation and (vii) the substrate purity as a function of the axial crystal position.