Study on the growth of Nd3+:Gd3Ga5O12 (Nd:GGG) crystal by the Czochralski technique under different gas flow rates and using different crucible sizes for flat interface growth

In the Czochralski growth of GGG/Nd:GGG, the percentage of oxygen flowing in the growth chamber plays an important role in eliminating or controlling a number of growth problems. In this paper we report the growth of Nd3+:Gd3Ga5O12 (Nd:GGG) crystal at different flow rates of argon and oxygen percentages (1–2%) and concluded that the optimum percentage is 1.0–1.2%. No effect on the crystal growth was observed while increasing the argon flow rate from 240 LPH to 420 LPH and by keeping same percentage of oxygen. The growth of Nd:GGG crystal by the Czochralski technique with a flat crystal/melt interface was also studied using different crucible sizes and under the same crystal growth conditions. In this study, it was found that the critical Reynolds number, which measures the flow driven by crystal rotation to achieve flat crystal/melt interface, is directly proportional to the crucible diameter. And the crucible diameter (D) is related with the crystal diameter (d) by equation D=Kωd2, where K is the proportionality constant and ω is the crystal rotation rate. We also found that for a given crucible, the critical Reynolds number remains the same even for different crystal diameters.

► This paper reports the growth of Nd:GGG crystal at different gas flows and crucibles. ► Optimum oxygen percentage is 1.0–1.2% and no effect by increasing argon. ► For flat interface, the critical Re is proportional to the crucible diameter. ► Crucible diameter (D) is related with crystal diameter (d) by D=Kωd2. ► For a given crucible and thermal condition, the critical Re remains constant.