籽晶台形状对PVT法同质外延生长氮化铝单晶初始生长的影响

借助专业晶体生长模拟软件FEMAG和自主开发的对流、传质、过饱和度及生长速率预测等有限元模块研究了物理气相传输法(PVT)同质外延生长氮化铝(AlN)单晶工艺时的初始传热及传质过程,并分析了不同形状籽晶台对生长室内的温度场、流场、过饱和度及生长速率的影响。温度场模拟结果表明籽晶台侧部角度改变可影响籽晶表面轴向及径向温度梯度,流场及传质模拟表明籽晶台侧部角度变化对籽晶台周边的传质有巨大影响。传质及过饱和度模拟结果表明,当籽晶台侧部角度为130°时,籽晶表面温度梯度较小且可以完全抑制籽晶台侧部多晶沉积,有利于通过同质外延工艺生长出无寄生、无裂纹的高质量氮化铝单晶锭。

Effects of Seed-Holder Shape on the Initial Growth of AlN Single Crystals by Homoepitaxial PVT Method

The initial temperature field and mass transport during homoepitaxial AlN growth process by the PVT method were studied by FEMAG and in-house developed convection,mass transport,supersaturation and growth rate prediction finite element modules.The influences of the seed-holder shape on the temperature field,flow field,supersaturation and growth rate were investigated in detail by numerical simulations.The simulation results show that the flow and mass transport near the seed-holder were strongly affected by the axial and radial temperature gradient near the seed deposition surface,and these temperature gradients near the seed deposition surface could be calibrated by the expansion angleθof the seed-holder.When the angleθof the seed-holder is 130°,the temperature gradient at seed surface is small and the polycrystalline deposition at the seed surface and seed-holder periphery can be completely prohibited,which is beneficial to grow parasitic-free,crack-free and high-quality AlN single crystals.