Fe、Co、Ni、Mn钝化多孔硅的制备、表面形貌和光致发光研究

【作者】 富笑男；

【导师】 李新建； 胡行；

【作者基本信息】 郑州大学 ， 凝聚态物理， 2001， 硕士

【摘要】 多孔硅表面钝化和表面形貌的控制技术具有重要的基础和应用研究价值。本文的第一部分用掺杂度较高的(ρ=3×10^-2Ω·cm)、取向为（111）的P型原始硅片水热制备了Fe、Co、Ni、Mn系列金属钝化多孔硅（MPS），重点研究了在不同制备条件下MPS的表面形貌和发光特性，取得了一系列新的结果：1．MPS样品的制备。研究了不同制备条件下（如腐蚀液中不同金属离子浓度，不同腐蚀时间等）所得样品的表面形貌和发光特性，找到了制备具有最佳表面形貌和最佳发光性能多孔硅样品的水热腐蚀条件。2．MPS表面形貌的研究。通过实验发现，MPS的样品的表面均存在相似的结构畴区，畴区间有明显的边界，畴区内由垂直于表面的、相互独立的结构单元组成。实验结果表明，降低腐蚀液中金属离子的浓度，增加腐蚀时间可以生长出表面形貌均匀的多孔硅样品。从而在一定程度上实现了MPS表面形貌的可控性。3．MPS发光特性的研究。通过分析发现，MPS样品的发光强度及发光峰的半高宽值依赖于样品的表面形貌的特征，即样品的表面形貌越均匀（指结构畴区、畴区内基本结构单元的尺寸和基本结构单元排列的规则性），样品发光强度就越强，发光峰的半高宽值就越小。由此，可以通过改变腐蚀条件人为地控制样品的表面形貌，并达到改善样品发光性能的目的。 作为对比，在论文的第二部分用HF酸和HF（LiF）+HNO₃水溶液作为水热腐蚀液，在不同条件下制备了氢钝化多孔硅（HPS），得到了如下结果：1．HPS样品的制备。用HF酸和用HF（LiF）+HNO₃水溶液作为腐蚀液，分别用（100）（ρ=15～25 Ω·cm）、（111）（ρ=15～25 Ω·cm）取向的P型单晶硅片制备了氢钝化多孔硅。2．HPS样品表面形貌的研究。1)用HF酸制备的和用HF+HNO₃制备的多孔硅样品表面形貌的对比。结果发现，两者的表面形貌截然不同，前者的表面由大量的深孔组成，而后者的表面由很多的硅岛组成。造成这一现象的原因可能是由于 郑州大学硕士学位论文 摘 要 制备过程中所用腐蚀液的不同而导致的腐蚀机理的不同。2)用HF＋HNO。制备 的多孔硅与MPS样品形貌的对比。两者的表面形貌有相似之处，即都由大量的 硅岛组成结构畴区。但前者表面存在很多尺寸较大的腐蚀坑，而后者没有。前者 表面均匀度不如后者的表面均匀度。3)用HF＋HNO3水热制备的多孔硅与用传 统的阳极腐蚀法制备的多孔硅的形貌的对比。前者表面的基本结构单元尺寸比后 者的小一个数量级，并且前者的单元之间排列比较紧密（～lum），而后者的单元 之间的间隙达到 10 u m。吗 3．HPS发光特性的分析。分析了用水热腐蚀法制备的具有的蓝光发射的多孔硅＿样品在RTO处理前后发光峰整体蓝移并由单发光峰变为两个发光峰的原因，分 析结果表明，上述现象是由于经RTO处理后的样品表面中硅纳米颗粒在整体减 小的同时出现了尺寸分离现象。这一结果说明多孔硅中短波长发射也具有强烈的 尺寸相关性。这为多孔硅发光的量子限域模型提供了新的证据。更多还原

【Abstract】 The technology of surface passivation and morphology controlling of porous silicon (PS) exhibits high scientific values for both fundamental and application research. In the first part of this thesis, a series of metal-passivated PS (MPS, M = Fe, Co, Ni, Mn) were fabricated by hydrothermally etching highly boron-doped ( p 3 X 1 02 Q ?cm ), ( 111 ) oriented single crystalline silicon wafers, and their morphologies and photoluminescence (PL) prepared under different etching conditions were investigated. Some new results were achieved. 1. Preparation of MPS. The characteristics of the morphology and the PL of MPS prepared under different etching conditions were studied, and through which, the most suitable conditions for the preparation process were obtained. 2. Morphology of MPS. It was found that the surfaces of all MPS samples were composed of similar structural domains with obvious domain boundaries. In each domain, large quantities of quasi-identical units were uniformly, independently arrayed perpendicular to the surface. Various experimental results disclosed that the regularity of the surface could be improved though adopting lower metal ion concentrations and increasing etching time. Tunable morphologies of MPS were generated. 3. PL of MPS. The dependence of the PL intensity and the full width at half maximum (FWI-IM) of the PL spectrum on the morphology of MPS were built up. The more the regularity of the surface (the size of structural domains and units, the regularity of units?array), the stronger the PL intensity and the smaller the FWHM. So PL properties of MPS might be improved through controlling the surface morphology. As comparison, hydrogen-passivated PS (HPS) was also prepared under different etching condition, with HF or HF (LiF) + LIMO3 as hydrothermal solutions. The results were got as follows. 1. Preparation of LIPS. HPS samples were prepared by hydrothermal etching technique with boron-doped, (100) oriented ( p = 15 ?25 Q ?cm ) and (Ill) oriented (p = 3 X 1 0~ Q . cm) single crystalline silicon wafers respectively. 2. Morphology of HPS. 1) Morphological comparison between the samples prepared with HF and I-IF+ HNO3. The results showed that the surface of the former is composed of a large number of deep holes and the latter a large number of separated silicon islands. The difference between their morphologies might originate from the difference of etching mechanisms which due to the different etching solutions. 2) Morphological comparison between the samples prepared with HF+ HNO3 and MPS. Both of their surfaces have structural domains composed of lots of silicon islands. But the morphology of the latter is much more regular than that of the former. 3) Morphological comparison between the sample prepared with HF+ lIMO3 and the normal PS. The structural unit size of the former is much smaller than that of the latter and the unit array of the former is more inseparable (? ii in) than that of the latter (10 ii in). 3. PL of LIPS. Blue-emitting porous silicon (PS) prepared by hydrothermal etching was treated by rapid thermal oxidation process. Accompanied with the blue shift of whole photoluminescence (PL) s更多还原