Fine structure of the melting process in pure CdTe and in CdTe with 2 mol% of Ge or Sn

Abstract

The melting process of pure CdTe as well as of CdTe+2 mol% Ge and CdTe+2 mol% Sn was investigated experimentally by means of differential thermal analyses. The samples were heated above their respective melting temperatures T m and annealed at various defined temperatures before continuation of heating. Volume fractions of clusters, remaining in the melt even above the melting point, were derived from the area of the corresponding thermal effects. It was confirmed that the melt consists in all cases of two types of structures: clusters (with a short-range order close to the crystalline substance) within an amorphous matrix. The size of the clusters was estimated from the activation energies of the crystallization process; they were found to consist of about 66 to 98 atoms in pure molten CdTe. For two cases, pure CdTe and CdTe+2 mol% Ge, ‘hot crystallization’ was observed, i.e. after a given heat treatment the melt crystallized at temperatures above T m.