生长温度对分子束外延AlN薄膜的影响

The Impact of Temperature on Molecular Beam Epitaxy Growth of AlN

研究了不同生长温度对分子束外延设备在蓝宝石衬底上外延AlN薄膜时对薄膜样品晶体质量和表面形貌的影响。研究发现:随着生长温度的提高,RHEED条纹更加纤细、更加细锐;在低温下,AlN表面有密集的小岛状晶粒结构,但随着温度的升高,小岛之间开始聚合,并形成大范围的原子力台阶,表明AlN薄膜在高温下有良好的二维生长模式;(002)和(102)面XRD半高宽结果进一步表明AlN薄膜的二维生长模式,且在高温下,AlN薄膜中的刃型位错密度大大减小。说明提高生长温度有助于提高AlN薄膜的晶体质量,获得平坦的表面。

In this paper, we studied how did the growth temperature affect the crystal quality and sur- face morphology of A1N films grown by molecular beam epitaxy. RHEED streaks become more and more slender with the increase of growth temperature. By means of AFM images, we found that in low temperature, there are lots of island-like grain structures on the A1N films surface. And the island be- gan to aggregate together and form a wide range of atomic steps with improving the growth tempera- ture. All of this indicate that there is a good two-dimensional growth mode. The results of XRD further illustrate the good two-dimensional growth mode. The density of edge dislocation in the A1N films has greatly reduced in the high growth temperature. All of the above mentioned showed that increasing the growth temperature helps to improve the crystal quality and obtain a flat surface.