MOCVD growth of (100)-oriented CeO2 thin films on hydrogen-terminated Ssi(100) substrates
MOCVD growth of (100)-oriented CeO2 thin films on hydrogen-terminated Ssi(100) substrates
复制标题
DOI：
10.1016/s0921-5107(98)00133-0
复制
发表时间：
1998-06-12
期刊：
影响因子：
--
通讯作者：
Suzuki, M
中科院分区：
文献类型：
--
作者：
Ami, T;Suzuki, M
具有萤石结构的氧化铈（CeO 2）由于其热稳定性和与Si的良好晶格匹配，被认为是在硅衬底上外延生长钙钛矿材料的理想缓冲层。另一方面，在形成CeO 2（100）方面仍然存在技术困难，与（111）取向的CeO 2相比，CeO 2（100）更具有应用吸引力。本文报道了以Ce（NO3）4为钼源，采用金属有机物化学气相沉积（MOCVD）方法在氢封端的Si（100）衬底上制备CeO 2薄膜。利用傅里叶变换红外衰减全反射（FT-IR-ATR）和原子力显微镜（AFM）研究了基底的表面微观粗糙度。用RCA法清洗的硅晶片浸泡在添加H_2O_2的0.5%HF溶液中进行氢终止，观察到优先的Si-H ~（2-）振动峰，并伴有弱的Si-H ~（2-）峰。通过AFM估计的基底的均方根粗糙度为约0.2nm。用X射线衍射（XRD）对样品的结晶度和取向度进行了表征。薄膜是多晶的，并且优先取向于[100]方向。由Lotgering定义的优先取向因子为0.83。利用保持发射扫描电子显微镜（FE-SEM）、原子力显微镜（AFM）和透射电子显微镜（TEM）对样品的微观结构进行了表征。晶粒呈“非等轴”柱状，以牺牲其他柱状物为代价垂直于表面生长。通过AFM表征的50 nm厚的膜的表面纹理为矩形形状，具有100 X 200 nm的典型尺寸。它们在相同的方向上排列，并且矩形的边缘平行于Si（011）面，这表明可能的面内取向。通过对150 nm厚的膜进行截面HR-TEM分析，确认在CeO 2/Si（100）界面形成的非晶层的厚度为2nm左右。(C)1998年Elsevier Science S.A. All rights reserved.
Ceria (CeO2) with a fluorite structure is supposed to be an ideal buffer layer for fabricating epitaxially grown perovskite materials on silicon substrates because of its thermal stability and excellent lattice match with Si. On the other hand, there are still technical difficulties in forming CeO2(100), which is more attractive for applications compared to that of (111) orientation. We report the preparation of CeO2 thin films on hydrogen-terminated Si(100) substrates by metal-organic chemical vapor deposition (MOCVD) using Ce(DPM)(4) as an MO-source. The surface microroughness of the substrates was investigated using Fourier-transform infrared-attenuated total reflection (FT-IR-ATR) and atomic force microscopy (AFM). Si-wafers cleaned by RCA method were immersed in H2O2-added 0.5% HF solutions for hydrogen-termination, and preferential Si-H-2 vibrational peaks accompanied with weak Si-H, peaks were observed. The root mean square roughness of the substrates estimated by AFM was around 0.2 nm. The crystallinity and orientation were characterized by X-ray diffraction (XRD). The films were polycrystalline, and preferentially orientated to the [100] direction. The preferential orientation factor defined by Lotgering was 0.83. The microstructures were characterized by a held-emission scanning electron microscopy (FE-SEM), an AFM and a transmission electron microscopy (TEM). The grains were 'non-equiaxed' columnar, growing perpendicular to the surface at the expense of other columns. The surface texture of a 50 nm-thick film characterized by AFM was rectangular in shape, with a typical size of 100 x 200 nm. They were aligned in the same direction, and the edges of the rectangular are parallel to the Si(011) facets, suggesting a possible in-plane orientation. Cross-sectional HR-TEM analyses of a 150 nm thick film verified the thickness of the amorphous layer formed at the CeO2/Si(100) interface to be around 2 nm. (C) 1998 Elsevier Science S.A. All rights reserved.