(001)Si衬底上La_(0·9)Sr_(0·1)MnO_3/SrTiO_3外延生长薄膜的界面电子显微学研究

Investigations of the interface structure of epitaxial La_(0.9)Sr_(0.1)MnO_3/SrTiO_3 film on Si substrate characterized by transmission electron microscopy

本文利用高分辨电子显微术、电子能量损失谱和电子全息技术对Si基体上生长的SrTiO3(STO)和La0.9Sr0.1MnO3(LSMO)薄膜及其STO层和Si基体之间的界面结构进行了深入研究,结果表明在Si和STO层之间由于氧扩散会形成一层过渡的SiOx无序层,且随沉积条件不同界面原子无序层厚度稍有不同;选区电子衍射结果表明薄膜和基体之间的外延生长关系为[001]LSMO//[110]Si,[110]LSMO//[001]Si[001]STO//[001]Si,[010]STO//[110]Si;电子能量损失谱分析表明界面无序层中Si离子的氧化态处于Si2+和Si0之间;电子全息结果清晰地显示了基体与薄膜之间存在明显的相位和势垒变化,负电荷聚集在界面SiOx的无序层中。

Interface structure of the La0.9 Sr0.1 MnO3/SrTiO3 （STO/LSMO） film on Si substrate has been investigated by transmission electron microscopy （TEM）, electron-energy loss spectroscopy （EELS）, and electron holography. TEM investigations indicated that the interfacial oxygen diffusion during film growth often results in an appearance of a thin SiOx layer in SrTiO3/Si films and related heterojunctions, and the thickness and microstructure of the SiOx interfacial layer change visibly from one sample to another grown under slightly different conditions. Electron diffraction observations demonstrated the epitaxial relationships in the LSMO/STO/Si heterojunction as [ 001 ] LSMO//[ ^-110 ] Si, [ 110 ] LSMO// [001]Si and [001 ]STO//[001 ]Si, [010]STO//[^-110]Si. The EELS analyses on the interfacial region indicated that the Si ions are in intermediate oxidation states in the amorphous layer and the interfacial Ti bonding changes slightly. Electron holography measurements indicated that notable negative charges accumulate in the amorphous SiOx layer.