原料空隙率对6H-SiC晶体生长初期的影响

Effects of the Porosity of the Source Materials on the Initial Growth of 6H-SiC Crystal

生长准备中不同的装料方式导致原料的空隙率不同.在其它生长工艺参数保持一致的前提下研究了不同空隙率的原料(50%、55%、60%)对SiC晶体生长初期生长速率和结晶质量的影响.实验发现,在晶体生长初期生长速率随原料空隙率的增大而升高,过快的结晶速率导致晶体的结晶质量下降.同时利用有限元方法模拟了不同空隙率的原料(50%、55%、60%)在生长初期内部温度场分布、质量输运以及晶体生长速度.因为在生长温度下原料内的热量传输主要依靠SiC颗粒间的热辐射,所以空隙率增大会导致其等效热导率增大.模拟结果表明:60%空隙率的原料最短时间内达到稳态传热,初期晶体生长速率最大.模拟的结果合理地解释了原料空隙率对SiC晶体生长初期的影响规律.

The source materials with different porosity were be prepared by different loading ways.Effects of the porosity（porosity： 50%,55%,60%） of the source materials on the crystal growth rate and the crystal quality in the initial stage of SiC crystal growth were investigated respectively.It is found that crystal growth rate rises and the crystal quality declines with the increase of the porosity of the source materials.The temperature distribution and mass transport in the source materials（porosity： 50%,55%,60%） as well as the growth rate in the initial growth stage are simulated by the finite element method.The heat transfer inside the source material under the typical growth temperature bases on thermal radiation between SiC granulas.The simulations indicate that it takes the least time to reach stationary heat transfer for the source materials with 60% porosity and its growth rate in the initial growth stage is the largest among them.Therefore,the simulations explain the results of the growth experiments very well.