【作者】 辛伍红；

【导师】 李垚；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2013， 博士

【摘要】 硅锗是一种很重要的半导体材料，具有很高的折射率，且其折射率可以通过改变其中锗的含量来调节。通过将硅锗填充至蛋白石结构的胶体晶体模板内可构筑反蛋白石结构有序大孔的硅锗产物，可能实现完全带隙光子晶体的制备。但在这个研究方向上存在着两个难题，第一是目前已有的制备硅锗的研究手段均存在着能耗高、需特殊设备等问题；第二是在构筑硅锗有序大孔结构的过程中常用手段面临填充率低下的难题。本文以简易的电沉积为制备手段，探讨以离子液体为溶剂制备硅锗并填充模板实现有序大孔结构的构筑，得到的有序大孔产物很好的反向复制了模板的结构。其中主要针对硅锗制备的工艺条件、填充深度（膜厚）与表面形貌的关系、叠层有序大孔产物的制备和高温条件下制备硅锗二维有序产物四个方面来进行研究。本文的主要研究内容如下：采用循环伏安法确定离子液体[EMIm]Tf2N和Py1,4Tf2N的电化学行为，结果表明该电化学过程属于非传质控制的准可逆过程，主要有两个还原峰，在-1.3V出现的还原峰对应的是Ge⁴⁺至Ge²⁺的还原过程，在-1.9V处对应的是硅锗共沉积峰；XPS测试结果表明产物中Si被完全氧化，而薄膜内部Ge为非完全氧化态；Raman测试结果显示产物中Ge的光学模在280cm-1处，属于非晶态。对氧化产物进行了高真空氢气还原处理，XPS结果显示产物中的Ge被部分还原，同时Raman结果表明其结晶度增大，但高真空处理对产物内部Si元素的价态无明显改善。研究了聚苯乙烯（polystyrene，PS）模板的光学性质，其中光通过PS模板后在³00°的空间内有较均匀的分布；结合Bragg-Snell方程对胶体晶体模板的带隙进行了分析，发现实际测量的带隙位置与计算值有6.7%的偏差；讨论了完全填充产物的形貌随填充厚度的变化情况，讨论得到当表面孔为圆形、近似三角形和反向三角形时对应的填充厚度分别为层数)，并分析了产生这种形貌的原因。探讨了制备有序大孔硅锗产物的可行性和制约因素，发现电解液对PS模板具有更好的润湿性，因而产物优先生长在微球表面；研究了沉积电位对制备过程的影响，发现在沉积电位小、沉积电流较大的情况下PS模板被破坏无法得到周期性结构，主沉积电位-1.9V为最佳实验电位；研究了模板的排列方式、模板与基底间的结合力和微球尺寸对产物的影响，发现直径400nm以下的微球组装的模板不适用于硅锗的填充，而通过填充与基底间结合力弱的模板得到的产物与硅锗薄膜的性质相似。率先尝试了在离子液体中制备Si/Ge和Al/Ge叠层有序大孔产物，研究发现第一叠层与基底的结合力对得到的产物质量起决定性作用。其中由于Si4+和Ge⁴⁺的电化学行为接近，Si/Ge叠层的制备与硅锗薄膜类似。而在对Al/Ge叠层的研究中，由于Al的生长速度较快，可通过调节Ge层的厚度、Al的沉积电位、Al的沉积时间等因素获得不同形貌的Al/Ge叠层有序大孔结构。产物中的Al按照“岛状”模式生长，获得的厚度较大的Al/Ge产物可以做为陷光材料。探索了在高温情况下进行离子液体电沉积制备硅锗和有序大孔硅锗的情况。在薄膜的制备过程中，温度促使生成较大、抗氧化性能较好的产物颗粒，Raman和XPS测试验证了这一结论。高温情况下制备的有序大孔结构具有“渔网”状的形貌，通过对机理的研究发现这一升温过程伴随着PS模板的软化和四氯化硅、四氯化锗的挥发过程；分析研究过程发现，产物的厚度不随电沉积时间的延长发生改变；同时对得到的有序大孔产物进行光谱表征，研究结果表明产物可以作为光栅和微棱镜使用，产生较纯的单色光。更多还原

【Abstract】 SixGe1-xis a very important semiconductor with high refractive index whichcould be adjusted by varying the content of Ge. Ordered macroporous SixGe1-xcouldbe obtained by filling the voids of the opaline photonic crystals, which makes itpossible to achieve complete band gap. However, there are two obstacles on thisresearch. First, special equipments are necessary to get SixGe1-xand the energyconsumption in normal methods is extremely high. Low filling ratio is the otherproblem faced when an ordered macroporous Si_xGe_1-xis prepared.In this paper, ionic liquids are used as solvent to prepare SixGe1-xfilm andordered macroporous Si_xGe_1-xthrough electrical deposition, the obtained materialwell retains the ordered macroporous structure of the templates. The fabricationconditions and the relationship between the infiltration depth （film thickness） andthe morphology are systematically studied. The preparation of the laminatedsemiconductor layer at room temperature is briefly discussed as well as thefabrication of two-dimensional ordered macroporous SixGe1-xat elevatedtemperature. The main contents of this paper are as follows:Ionic liquid [EMIm]Tf₂N and Py_1,4Tf₂N are used as solvent while siliconchloride and germanium chloride are used as solute. Cyclic voltammetry is used toevaluate the electrochemical behaviors of ionic liquids on ITO, copper and platinumsputter-coated silicon substrates. The reduction potentials and the control step of theelectrode reaction are studied on ITO substrate. The results present that theelectrochemical process is a non-mass transfer limited reaction and there are tworeduction peaks during the process. The peak centered at-1.3V is correlated with thereduction of Ge（IV） to Ge（II）, and a more negetive wave centered at-1.9V could becontributed to the co-deposition of silicon and germanium.XPS results reveal that silicon contained in product is totally oxidized whilegermanium is partially oxidized. In Raman analysis, the peak at280cm^-1corresponds to longitudinal optical phonon vibration of amorphous Ge-Ge. Thepartially oxidized film is heated under high vacuum with rather low hydrogen partialpressure. The heat-treated products are then analysed by XPS and Raman, the resultsillustrate that GeO₂could be partially reduced to GeO and Ge. However, the thermaltreatment has no impact on SiO₂.The optical properties of polystyrene template are studied to get theinformation on the spatial distribution of light incidents on the ordered structure.The deviation between the measured position of bandgap and the calculated one according to Bragg-Snell equation is6.7%. The observed surface morphology of3-D ordered macroporous products along the （111） direction is discussed in terms ofsubsequently increasing film thickness. Models are set up to help with fullunderstanding of the evolution of the morphology （the shapes of the pore mouthsand pore walls）. When the film thickness isFeasibility and constraints of the preparation of ordered macroporous SixGe1-xare investigated. The contact angles of the solvent on PS template and on ITOsubstrate are tested, confirming that the solvent has better wettability to PS templateand the product is deposited around the microspheres priorly. The effect ofdeposition potential is studied, the result reveals that the ordered structre of thetemplate is destroyed if a more negative potential is applied during the deposition.The potential of-1.9V is more suitable for the co-deposition of silicon andgermanium. The effect of packing modes of templates, the adhesion of the templateto substrate and the diameters of PS spheres are also studies. The results indicatethat the deposit could not be infiltrated into the interstitial space of templateassembled from PS spheres with diameters smaller than400nm, and the physicalproperties of SixGe1-xobtained if the adhesion is weak is similar to film product.Si/Ge laminated and Al/Ge laminated ordered macroporous materials areprepared for the first time. The adhesion of the first layer to substrate plays aimportant role in determining the morphology of the product. For the fabrication ofSi/Ge laminated ordered macroporous material, Ge layer is deposited on PS-coatedITO substrate first, and then Si layer is deposited on the top of the Ge layer.However, the deposition of Al/Ge laminated ordered macroporous layers is morecomplicated for the fast deposition rate of aluminum. Al/Ge laminated product canbe obtained by modifying the thickness of germanium deposit, the depositionpotential and the deposition time of aluminum. The growth mode of aluminum isVolmer-Weber, leaving an uneven film surface.Research on the electrodeposition of SixGe1-xfilm and ordered macroporous Si_xGe_1-x in ionic liquid at elevated temperature is carried out. XPS and Ramanresults reveal that the grain sizes of the product are increased as the temperatureincreases, so does the resistance of the particles to oxide. Atwo-dimensional orderedmacroporous film is prepared through electrodeposition at elevated temperature. Theformation of the2-D architecture could be due to the soften of polystyrene templateaccompanied with the evaporation of silicon chloride and germanium chloride.Moreover, the thickness of the product is limited to a radiu of the PS spheres.Product obtained by this method could used as gratings, generating monochromaticlight.更多还原