Li Xu, Zhao Jianyun, Liu Ting, Lu Yong, Zhang Jicai
College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing 100029, China.
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
Materials (Basel). 2021 Mar 31;14(7):1722. doi: 10.3390/ma14071722.
Aluminum nitride (AlN) films were grown on the m-plane sapphire by high-temperature hydride vapor phase epitaxy (HVPE). The effect of high-temperature nitridation on the quality of AlN film was studied. The high-temperature nitridation is favorable for the formation of semi-polar single (101¯3) orientation AlN film, the quality of which shows strong dependence on the nitridation temperature. The full width at half maximum of X-ray diffraction for (101¯3) AlN film was only 0.343° at the optimum nitridation temperature of 1300 °C. It is found that the nano-holes were formed on the surface of substrates by the decomposition of sapphire in the process of high-temperature nitridation, which is closely related to the quality improvement of AlN. At the critical nitridation temperature of 1300 °C, the average size of the nano-holes is about 70 nm, which is in favor of promoting the rapid coalescence of AlN micro-grains in the early stages. However, the size of nano-holes will be enlarged with the further increase of nitridation temperature, which begins to play a negative role in the coalescence of AlN grains. As a result, the grain size will be increased and extended to the epilayer, leading to the deterioration of the AlN film.
通过高温氢化物气相外延（HVPE）在m面蓝宝石上生长氮化铝（AlN）薄膜。研究了高温氮化对AlN薄膜质量的影响。高温氮化有利于形成半极性单一（101¯3）取向的AlN薄膜，其质量对氮化温度有很强的依赖性。在1300℃的最佳氮化温度下，（101¯3）AlN薄膜的X射线衍射半高宽仅为0.343°。研究发现，在高温氮化过程中，蓝宝石分解在衬底表面形成纳米孔，这与AlN质量的提高密切相关。在1300℃的临界氮化温度下，纳米孔的平均尺寸约为70nm，有利于在早期促进AlN微晶的快速合并。然而，随着氮化温度的进一步升高，纳米孔的尺寸会增大，这开始对AlN晶粒的合并产生负面影响。结果，晶粒尺寸会增大并延伸到外延层，导致AlN薄膜质量恶化。
