MOCVD生长GaN和GaN∶Mg薄膜的对比研究

COMPARATIVE ANALYSIS OF CHARACTERISTICS OF GaN AND GaN∶Mg FILMS GROWN BY MOCVD

对在SiC衬底上采用MOCVD方法制备的GaN和GaN :Mg薄膜进行X射线衍射 (XRD)、扫描电镜 (SEM)和拉曼散射光谱的对比研究发现 :两种样品均处于张力作用之下 ,但是GaN∶Mg样品却由于Mg的掺杂会在样品中引入更多的缺陷和位错加剧薄膜的无序化程度 ,致使薄膜质量变差 ;其次因为Mg原子半径比Ga原子半径大 ,所以当Mg替代Ga以后会引发压力应力 ,从而使薄膜张力减小 ,最后通过计算说明对于GaN :Mg样品而言 ,除了载流子以外 ,薄膜质量同样也会对A1(LO)

Mg-doped and undoped GaN epilayers were grown by metalorganic chemical vapor deposition on SiC substrates. The samples are both under tensile stress, while compared with undoped GaN, Mg doping would introduce much more defects and aggravate disorder so that the quality of film became worse. On the other hand, for the radius of Mg atom is larger than that of Ga, the compressive stress was introduced and tension in film decreased when Mg substituting Ga. Finally, we show as to the GaN. Mg epilayer, the quality. of film would also influence the A(1) ( LO) mode besides free carriers.