Growth of nonstoichiometric PbTe crystals by the vertical Bridgman method using the axial-vibration control technique

A modification of the vertical Bridgman method with the excitation of low-frequency axial vibrations in the melt (axial-vibration control technique) is developed to grow crystals of volatile chemical compounds. It is shown that the use of the axial-vibration control technique in the growth of PbTe crystals makes it possible to obtain a more uniform distribution of the excess (nonstoichiometric) component over the crystal length. As a result of the intense melt mixing, equilibrium between the vapor phase, the melt, and the growing crystal is fixed so rapidly that it becomes possible to change the nonstoichiometry of a growing crystal by changing the vapor pressure. The composition of the congruently melting lead telluride, determined by comparing the nonstoichiometries of the initial charge and the crystal grown, was found to correspond to (2.8 ± 0.3) × 10−4 mol excess Te/mol PbTe.