The Effects of ACRT on the Growth of ZnTe Crystal by the Temperature Gradient Solution Growth Technique

Abstract

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.

Growth of Single-Crystal Cd0.9Zn0.1Te Ingots Using Pressure Controlled Bridgman Method

“…Figure 1c shows the ACRT rotation sequence that was used during growth, where we used fast accelerating and slow decelerating steps. This method is effective in preventing Te accumulation at the growth interface, both at the center and near the ampoule's inner wall [14]. Growth proceeded for approximately 10 days with 1 mm/h pulling rate followed by annealing at 850 °C for 72 hours.…”

Numerical Simulation of Thermal-Solutal Capillary-Buoyancy Flow of Ge1–xSix Single Crystals Driven by Surface-Tension and Rotation in a Czochralski Configuration

“…Unfortunately, the rotations of crystals and crucibles were not taken into consideration, which is an essential industrial practice for improving the quality of crystals in the Cz crystal growth process. A lot of previous works focusing on the melt flow and the flow instability have not yet paid attention to solute diffusion in binary alloys [27][28][29][30]. Therefore, it is indispensable to carry out numerical simulations to precisely understand the influences of rotating crystals and crucibles on the thermal-solutal capillary-buoyancy convections in a Cz configuration.…”