m面AlN单晶自发成核生长表征

Characterization of m-Plane AlN Single Crystals Grown by Spontaneous Nucleation

采用金属系统物理气相传输(PVT)法自发成核方式,生长获得长宽均大于1 cm、厚度为毫米量级的m面AlN单晶块体。通过对不同m面AlN单晶生长宏观形貌、微观表面的测试分析,初步可判定其生长存在单核生长和多核生长两种模式。并将m面AlN晶体生长过程分为3个阶段,分别为生长中心形成阶段、生长阶段和生长台阶并组阶段。第一性原理计算表明,每生长一层(4个)Al-N基元的m面和c面AlN晶体释放的能量分别为2.76 eV和8.64 eV,通过对衬底厚度的调节可以初步控制m面AlN晶体的成核概率。以此为依据进行m面AlN单晶接长实验,获得了12 mm×20 mm尺寸的m面AlN单晶,最大厚度达5 mm,为进一步籽晶生长和器件制备提供技术及理论基础。

The m-plane AlN single crystals grown by spontaneous nucleation with length and width greater than 1 cm and thickness in millimeter scale were obtained by using metal system physical vapor transport(PVT)method.Two modes of mononuclear growth and multinuclear growth were determined by the test and analysis of macroscopic and microscopic surface of different m-plane AlN single crystals.The growth process form the m-plane AlN crystal can be divided into three stages,which were the growth center formation stage,the growth stage and the growth step combination stage.The first-principles calculations show that the energies released from the m-plane and c-plane AlN crystals(a layer of four Al-N primitives)are 2.76 eV and 8.64 eV,respectively.The nucleation probability of the m-plane AlN crystal can be controlled by the adjustment of the substrate thickness.Based on this,the m-plane AlN single crystal extension experiment was carried out,and an m-plane AlN single crystal with the size of 12 mm×20 mm was obtained with a maximum thickness of 5 mm.Meanwhile,this experiment provided the technical and theoretical basis for seed crystal growth and devices preparation.