偏晶向SiC籽晶上生长的AlN单晶

AlN Single Crystal Grown on Off-Orientation SiC Seed

采用物理气相传输法在自制[0001]偏8°晶向6H-SiC衬底上制备了直径42 mm、厚度320μm的连续AlN单晶层,c轴方向生长速率为32μm/h。AlN单晶层具有明显鱼鳞状宏台阶流生长表面特征。裂纹完全单向平行分布,且与台阶走向一致,其成因与台阶对热应力的吸收作用有关。未发现明显的穿线缺陷。发现AlN-SiC界面存在双角锥空腔,其起因是生长初期界面处未被AlN完全密实覆盖的微小区域,在生长过程中因内部温差不断发生的升华和凝华的自我调制过程。喇曼光谱和X射线衍射测试显示该层结晶性较好,(0002)面X射线摇摆曲线半高宽为76 arcsec,喇曼光谱E1(TO)模的半高宽为7.5 cm-1。

An AlN single crystal layer up to 42 mm in diameter and 320 μm in thickness has been grown on 6H-SiC seed with 8° off-orientation angle in respect to the c-axis by physical vapor transport method.The AlN layer is grown with a growth rate of 32 μm/h.The as-grown surface exhibits fish scale-like macro-step fluid growth characteristics.The crystal contains a few cracks which are parallel and in the same direction with step spread.The crack form is related to the thermal stress absorption effect of steps.Threading defects are not found,but double-pyramidal cavum defects are observed at SiC-AlN interface,which originated from the continuous sublimation and desublimation self-adjustment process in areas which are not covered with AlN at initial growth stage.Raman spactra and XRD measurements indicate that the layer has higher crystalline quality.The full width at half maximum（FWHM） of（0002） X-ray diffraction rocking curve is 76 arcsec and the FWHM of Raman spectra E1（TO） mode is about 7.5 cm-1.