Thermal oxidation of amorphous germanium thin films on SiO 2 substrates
Thermal oxidation of amorphous germanium thin films on SiO 2 substrates
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SiO 2 衬底上非晶锗薄膜的热氧化
DOI：
10.1088/0268-1242/31/12/125017
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发表时间：
2016
影响因子：
1.9
通讯作者：
De Los Santos Valladares L
中科院分区：
文献类型：
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作者：
De Los Santos Valladares L
在这项工作中，我们报告了空气中非晶锗 (a-Ge) 薄膜（140 nm 厚度）的热氧化。在SiO 2 衬底上采用常规热蒸发法制备后，样品在空气中在300至1000 C的不同温度下进行退火。通过X射线衍射、X射线反射率、同步加速器掠入射广角X射线散射和截面透射电子显微镜分析发现，a-Ge薄膜在475 C突然结晶，同时增加了a-Ge薄膜中氧化物（GeO 2）的厚度。层层时尚。 X射线光电子能谱表明GeO 2 层中Ge原子的氧化态为4+。然而，在500℃和550℃之间发生GeO 2 /Ge界面处的反应，将氧化物层还原为GeO x (x<2)并包含Ge 2+ 和Ge+。氧化层的厚度随着退火温度的增加而增长，遵循阿伦尼乌斯行为，活化能为0.82±0.09 eV，直至500℃。值得注意的是，我们在450℃–500℃的温度区间内观察到a-Ge的氧化和结晶同时增强，其中氧化速率在500℃左右达到最大值，约为0.8nmC−1。
In this work we report the thermal oxidation of amorphous germanium (a-Ge) thin films (140 nm thickness) in air. Following fabrication by conventional thermal evaporation on SiO 2 substrates, the samples were annealed in air at different temperatures ranging from 300 to 1000 C. By means of x-ray diffraction, x-ray reflectivity, synchrotron grazing-incidence wide-angle x-ray scattering and cross-sectional transmission electron microscopy analysis it is found that the a-Ge films abruptly crystallize at 475 C, while simultaneously increasing the thickness of the oxide (GeO 2) in a layer by layer fashion. X-ray photoemission spectroscopy reveals that the oxidation state of the Ge atoms in the GeO 2 layer is 4+. However, a reaction at the GeO 2/Ge interface occurs between 500 and 550 C reducing the oxide layer to GeO x (x< 2) and containing Ge 2+ and Ge+. The thickness of the oxide layer grows with the annealing temperature following an Arrhenius behavior with an activation energy of 0.82±0.09 eV up to 500 C. Remarkably, we observed simultaneous enhancement of the oxidation and crystallization of the a-Ge in the temperature interval 450 C–500 C, in which the oxidation rate reaches a maximum of around 0.8 nm C− 1 at around 500 C.