3C-SiC/Si(111)的掠入射X射线衍射研究

在衬底温度为1000℃条件下, 利用固源分子束外延(SSMBE)技术在Si衬底上生长3C-SiC单晶薄膜. RHEED结果显示在Si(111)上所生长的SiC薄膜为3C-SiC, 并与衬底的取向基本一致. 采用同步辐射掠入射X射线衍射(GID)技术并结合常规X射线衍射(XRD)研究了SiC薄膜内的应变和晶体质量. 常规衍射的联动扫描曲线得到薄膜处于双轴张应变状态. 3C-SiC薄膜和Si衬底的晶格失配和热膨胀系数失配是导致双轴张应变的原因. 根据不同角度的掠入射衍射Phi扫描的摇摆曲线结果, 发现薄膜晶体质量在远离SiC/Si界面区变好. 这是由于SiC薄膜中的缺陷随着远离界面逐渐减少的原因. GID和XRD的摇摆曲线结果表明薄膜中镶嵌块的倾斜大于扭转, 表明SiC薄膜在面内的晶格排列要比垂直方向更加有序.

Study on 3C-SiC/Si(111) by X-ray Grazing Incident Diffraction

Monocrystalline 3C-SiC films were successfully grown on Si(111) substrate at substrate temperature of 1000℃ by molecular beam epitaxy (MBE) using solid-state element C and Si sources. The RHEED results indicate that the film grown on Si(111) substrate is 3C-SiC film with all cubic axes parallel to the substrate. The quality and the strain of the film were investigated by Synchrotron radiation X-ray grazing incident diffraction method (GID) combining X-ray diffraction (XRD). The result shows that the film is in the state of biaxial tensile strain. The biaxial tensile strain is attributed to the large lattice and thermal expansion coefficient mismatch between SiC and Si. According to the result of the rocking curves of the film at different grazing incident angles, the quality of the film is better in the zone far from the interface between SiC and Si due to the decrease of the defects in the zone far from the interface. The results of rocking curves of GID and XRD show that the tilt mosaic is bigger than the twist mosaic in the SiC film, which indicat that the lattice array in plane is in better order than that in perpendicular direction.