2005, Vol.15, No.4

Journal of the Korean Crystal Growth and Crystal Technology 2023 KCI Impact Factor : 0.19

pISSN : 1225-1429 / eISSN : 2234-5078
https://journal.kci.go.kr/jkcgct

A numerical analysis was performed on magnetic field effects of silicon melt motion in Czochralski crystalpuller. The turbulent modeling was used to simulate the transport phenomena in 8" single crystal growing proces. Forsmall crucible angular velocity, the natural convection is dominant. As the crucible angular velocity increase, the forcedthe natural and forced convection near the crucible and the temperature profiles of the silicon fluids is similar to the caseof conduction.Key words Magnetic field effects, Czochralski crystal puller, Transport phenomena, Single crystal growing process,Natural convection, Forced convection, Temperature profiles, Silicon fluids, Conduction

Thermal-fluid analysis was performed to understand the thermal behavior in the horizontal CVD reactor, thereby, to design a susceptor which has a uniform deposition rate during silicon EPI growing. Four different types of susceptor designs, standard (no hole susceptor), hole #1 (240mm), hole #2 (150mm) and hole #3 (60mm), were simulated by CFD (Computational Fluid Dynamics) tool. Temperature, gas flow, deposition rate and growth rate were calculated and analyzed. The degree of flatness of EPI wafer loaded on the susceptor was computed in terms of silicon growth rate. The simulation results show that the temperature and thermal distribution in the wafer are greatly dependent on inner diameter of hole susceptor and demonstrate that the introduction of hole in the susceptor can degrade wafer flatness. Maximum temperature difference appeared around holes. As the diameter of the hole decreases, flatness of the wafer becomes poor. Among the threes types of susceptors with the hole, optimal design which resulted a good uniform flatness (5%) was obtained when using hole #1.

Color enhancement of African rubies with dark red was caried out by the heat treatment and the hydrothermaltreatment method respectively. The heat treatment method brought about an adverse effect causing the color to bedeteriorated. However, the hydrothermal treatment method enhanced its color and clarity. The hydrothermal treatmentconditions for color enhancement of them were as follows: solvent: 0.9 M Na2CO3-1 M K2CO3, temperature: 450oC,duration: 48 hrs, filling: 30 %, presure: 375 atm. As the results of characteristics for African rubies obtained under theseconditions, it was known that the amount of Cr3+, Fe3+, Ti4+ was reduced after the hydrothermal treatment from the ICP/MSand XRF analyses. Also, it was found that the red color from the colorimeter analyses was getting lighter. These resultswere consistent with the PL analysis showing that the intensity of the luminescence peak generated by the electrontransition of Cr3+Key words African ruby, Color enhancement, Aggregation, Hydrothermal treatment method, Heat treatment method