Crystalline structures of YAlO3 single crystal at high temperatures

In order to clarify the influence of high temperature annealing on a next-generation gate insulating material YAlO₃, single crystal YAlO₃ samples were annealed at various temperatures from 900 to 1300°C in air for about 12 hours. The crystalline structure was examined by X-ray diffractometry, while the surface profile was examined by atomic force microscopy and a surface profilometer. Furthermore, infrared absorption spectroscopy and optical microscopy were used. As a result, the following serial changes in structure were estimated. The perovskite structure of crystalline YAlO₃ starts to collapse and Y₃Al₅O₁₂ (YAG) is formed by the annealing at 1160 °C. Then, it segregates to Al₂O₃ andYAlO₃ after the annealing at 1300 °C.