蓝宝石衬底上生长的铝镓氮外延膜的应变分析

Strain Analysis of AlGaN Epitaxial Film Grown on Sapphire Substrate

采用金属有机化学气相沉积(MOCVD)方法制备了不同Al组分含量的2μm厚Al_xGa_(1-x)N外延膜,通过透射电镜定性分析了外延膜中的位错和缺陷,通过高分辨X射线衍射试验对Al_xGa_(1-x)N外延膜进行ω/2θ扫描,结果显示外延膜为六方晶系纤锌矿结构,通过对对称面和非对称面的晶面间距进行修正精确计算了外延膜晶格常数,并由此对应变进行定量分析,四个不同Al组分的Al_xGa_(1-x)N外延膜样品的四方畸变值随Al含量的增大而逐渐减小,并且均小于零,在水平方向上均处于压应变状态。

AlxGal-xN epitaxial films with different A1 component contents were preparated by metal organic chemical vapor deposition （MOCVD） method. Defects and dislocations in epitaxial films were analyzed by TEM. ω/2θ scan of AlxGal-xN epitaxial films was measured by high resolution X-ray diffraction test. The results show that the epitaxial films are hexagonal wurtzite structure, lattice constants of symmetry and asymmetry planes are calculated by correcting the crystal plane distances and the strain of epitaxial films is analied. The tetragonal distortion of epitaxial films is less than zero and reduces with the A1 content increasing, the compressive strain exists in horizontal direction.