Rotatable Offner imaging system for ellipsometric measurement
Rotatable Offner imaging system for ellipsometric measurement
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用于椭偏测量的可旋转 Offner 成像系统
DOI：
10.1149/2.0321612jss
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
and M. Uehara
中科院分区：
文献类型：
--
作者：
L. Jin;T. Tanaka;E. Kondoh;B. Gelloz;K. Sano;I. Fujio;Y. Kajiyama;and M. Uehara
通过原位记录单色光照射下的光电流来监测多孔硅（PSi）在HF乙醇溶液中的化学溶解过程，并将其作为光透射率的测量指标。建立了溶解时间、孔隙率和吸收系数之间的关系，并推导了吸收系数的孔隙率依赖性，从60%孔隙率到100%孔隙率。考虑到有效介质近似的Bruggeman模型和文献中的其他测量，以及量子限制（QC）和表面态的影响，吸收结果进行了讨论。清晰地观察到吸收光谱中QC的孔隙率和光谱依赖性。发现蓝色光谱范围（< 500 nm）中的QC需要极高的孔隙率（> 85%），这与红色至绿色区域相反，在红色至绿色区域中，QC被确定为研究的整个孔隙率范围。我们的方法允许连续探索各种孔隙率，而不限于高侧，同时保持理想的氢封端的PSi表面和非常好的结构完整性，因为PSi总是保持在HF溶液中，从不干燥。该研究还允许测定硅在各种HF基溶液中的溶解速率。
The progress of the chemical dissolution of porous silicon (PSi) formed from lightly-doped p-type silicon in ethanoic HF solutions was monitored by recording in situ the photocurrent from monochromatic illuminations, which was used as a measure of optical transmission. The relations between dissolution time, porosity, and absorption coefficient were established and the porosity-dependence of the absorption coefficient derived from∼ 60% porosity to 100% porosity. The absorption results were discussed considering the Bruggeman model of effective medium approximation and other measurements from the literature, together with the effects of quantum confinement (QC) and surface states. The porosity and spectral dependences of the QC in the absorption spectra were clearly observed. QC in the blue spectral range (< 500 nm) was found to require extremely high porosities (> 85%), contrary to the red to green region, where QC was identified for the whole porosity range studied. Our procedure allows the continuous exploration of a wide range of porosities, without limitation on the high side, while preserving an ideal hydrogen-terminated PSi surface and very good structural integrity, as PSi is always kept in HF solution and never dried. The study also allows the determination of the dissolution rate of silicon in various HF-based solutions.