The effects of ACRT on the growth of ZnTe crystal by the temperature gradient solution growth technique

Abstract

A finite element method is used here to simulate the temperature field, the thermosolutal convection, the solute segregation, and the non-isothermal phase transformation during the growth of ZnTe crystal via the temperature gradient solution growth technique (TGSG) with an accelerated crucible rotation technique (ACRT). Three different trapezoid-wave ACRT sequences are proposed, and their effects are examined from the views of the constitutional supercooling and the mixing of the solution. The solution in front of the growth interface can be fully mixed only during the constant rotation stage of the ACRT when there is a clockwise Ekman flow. An inappropriate ACRT can produce excessively strong clockwise and counterclockwise Ekman flows, and this results in constitutional supercooling in front of the central part of the growth interface at the beginning of the stop stage and in front of the peripheral part at the end of the constant rotation stage. By adjusting the acceleration rate of the ampoule rotation, the appropriate Ekman flows can be obtained to well mix the solution and avoid the constitutional supercooling. An appropriate ACRT sequence is provided, which can facilitate the mixing of the solution, avoid constitutional supercooling, and improve the growth interface morphology.