Surface reconstructions in molecular beam epitaxy of SrTiO3
Surface reconstructions in molecular beam epitaxy of SrTiO3
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DOI：
10.1063/1.4901726
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发表时间：
2014-11-10
影响因子：
4
通讯作者：
Stemmer, Susanne
中科院分区：
文献类型：
--
作者：
Kajdos, Adam P.;Stemmer, Susanne
结果表明，反射高能电子衍射(RHEED)可以作为一种高灵敏度的工具来跟踪(001)SrTiO_3薄膜的吸附限制分子束外延的表面和所产生的薄膜的化学计量。即使在生长条件下，生长出的薄膜的晶格参数与化学计量比的大块晶体的晶格参数在高分辨率X射线衍射(XRD)的检测下限内相同，表面重建也发生了从(1×1)到(2×1)到c(4×4)的变化，随着钛金属有机源的等效束流压力的增加。这些表面重构与从混合的SRO/二氧化钛终止到纯的二氧化钛终止相关联。在生长开始时观察到的RHEED振荡的相移中，也明显地表现出向二氧化钛表面的过渡终止。与已有的掺杂薄膜载流子迁移率的结果比较表明，最佳的薄膜生长条件是在X射线衍射窗内的二氧化钛饱和表面[c(4×4)重构]。(C)2014 AIP出版有限责任公司。
We show that reflection high-energy electron diffraction (RHEED) can be used as a highly sensitive tool to track surface and resulting film stoichiometry in adsorption-limited molecular beam epitaxy of (001) SrTiO3 thin films. Even under growth conditions that yield films with a lattice parameter that is identical to that of stoichiometric bulk crystals within the detection limit of high-resolution x-ray diffraction (XRD), changes in surface reconstruction occur from (1 x 1) to (2 x 1) to c(4 x 4) as the equivalent beam pressure of the Ti metalorganic source is increased. These surface reconstructions are correlated with a shift from mixed SrO/TiO2 termination to pure TiO2 termination. The crossover to TiO2 surface termination is also apparent in a phase shift in RHEED oscillations observed at the beginning of growth. Comparison with prior results for carrier mobilities of doped films shows that the best films are grown under conditions of a TiO2-saturated surface [c(4 x 4) reconstruction] within the XRD growth window. (C) 2014 AIP Publishing LLC.