First-principles Calculations and Fabrication of Si-based Nanostructures and their Structural and Optical Properties

众所周知，以Si作为基质材料的微电子技术是当今信息化时代的关键支柱，已经达到相当成熟的规模产业化水平，在信息高科技领域中做出了巨大的贡献。然而，由于体Si为间接带隙材料的内在秉性制约了信息化社会发展的光电子集成发展需求，实现Si基高效发光是硅基光子学亟待突破的关键课题。目前，Si基纳米结构表现出良好的光学性质，成为实现Si基高效发光最有潜力的材料之一。但是，Si基纳米结构的分布随机性、尺寸分布不均匀、密度难提高及其发光机制仍不统一等制约了发光效率进一步提高。本文通过UHVCVD外延薄膜技术和电化学阳极腐蚀相结合的方法制备了Si、SiGe纳米结构，结合第一性原理计算方法，系统地研究了Si、SiG...It is well known that Si microelectronics is the key pillar of information age at present. As the main material for microelectronics, Si possesses quite mature fabrication technology which has contributed greatly to the high-tech information industry. However, a major obstacle imposed on Si is its indirect interband transition (i.e. the indirect bandgap) property,which has limited the development ...学位：理学博士院系专业：物理与机电工程学院物理学系_凝聚态物理学号：1982006015317

Structure design and preparation of porous SiGe/Si heterostructure material microcavity

提出了采用多孔SIgE/SI异质多层结构来获得布拉格反射镜方法.首先采用传输矩阵方法设计了多孔SIgE/SI异质材料微腔结构,并通过超高真空化学气相沉积与电化学阳极腐蚀相结合的方法实验制备了两种结构的微腔,同时对微腔进行光学性质表征,并详细讨论了实验结果.We propose a method for preparing the Bragg reflectors by porous SiGe/Si heterogeneous multilayer structure.Two kinds of structure of porous SiGe/Si microcavity are prepared through a method by combining ultra-high vacuum chemical vapor deposition and electrochemical anode,based on the numerical simulations of transfer matrix method.The optical properties of the microcavity are characterized,and the experimental results are discussed in detail.福建省省教育厅基金项目(JB11128);闽江学院科技启动项目(KQ1004

Photoluminescence properties of selenium nanocrystals on Si(100) substrate formed by rapid thermal annealing

由于尺寸缩小引起的量子效应,硒(SE)材料的低维纳米结构具有更高的光响应和低的阈值激射等特性,因此成为纳米电子与纳米光电子器件领域一个重要的研究方向.本文通过对非晶硒薄膜的快速热退火来制备硒纳米颗粒,退火温度在100—180 C之间时,结晶后的硒纳米颗粒均为三角晶体结构,其颗粒尺寸随退火温度的增加而线性增大.光致发光谱测试发现三个发光峰,分别位于1.4 EV,1.7 EV和1.83 EV.研究发现位于1.4 EV处的发光峰来源于非晶硒缺陷发光,位于1.83 EV处的发光峰来源于晶体硒的带带跃迁发光;而位于1.7 EV处的发光峰强度随激发功率增强而指数增大,且向短波长移动,该发光峰应该来源于非晶硒与硒纳米颗粒界面处的施主-受主对复合发光.We have investigated the structure and photoluminescence(PL) properties of Se nanocrystals(NCs) obtained by rapid thermal annealing of a-Se films on Si substrate.The size of Se NCs in a trigonal phase increases linearly with increasing temperature.Moreover,three PL peaks located at 1.4,1.7 and 1.83 eV are observed,which are attributed to the emission of defects in amorphous Se,donoracceprter pair(DAP) recombination at the interface of amorphous Se and Se NCs,and interband transition of Se crystals,respectively.华侨大学科研基金(批准号:12BS226); 福建省自然科学基金(批准号:2012J01277;2012J01284); 国家重点基础研究发展计划(批准号:2012CB933503); 国家自然科学基金(批准号:61036003;61176050;61176092;60837001); 福建省教育厅基金项目(A类)(批准号:JA12270)资助的课题~

Growth of Thick Ge Epitaxial Layers with Low Dislocation Density on Silicon Substrate by UHV/CVD

采用超高真空化学气相淀积系统,以高纯Si2H6和GeH4作为生长气源,用低温缓冲层技术在Si(001)衬底上成功生长出厚的纯Ge外延层.对Si衬底上外延的纯Ge层用反射式高能电子衍射仪、原子力显微镜、X射线双晶衍射曲线和Ra-man谱进行了表征.结果表明在Si基上生长的约550nm厚的Ge外延层,表面粗糙度小于1nm,XRD双晶衍射曲线和Ra-man谱Ge-Ge模半高宽分别为530″和5.5cm-1,具有良好的结晶质量.位错腐蚀结果显示线位错密度小于5×105cm-2.可用于制备Si基长波长集成光电探测器和Si基高速电子器件.Thick Ge epitaxial layers are grown on Si(001) substrates with low temperature buffer layers with ultra-high vacuum chemical vapor deposition systems using Si2H6 and GeH4 as precursors.The deposition process of the Ge layer on Si is investigated in real time by reflection high-energy electron diffraction,and the quality of the Ge layer was evaluated by atomic force microscopy,double crystal X-ray diffraction(XRD),and Raman measurement.The root-mean-square surface roughness of the Ge epilayer with a thickness of 550nm is less than 1nm and the full-width-at-half maximum of the Ge peak of the XRD profile and the Ge-Ge mode of the Raman spectra are about 530″ and 5.5cm-1,respectively.These measurements indicate that the Ge epitaxial layer is of good quality.The etch pit density related to threading dislocations is less than 5×105cm-2.This is a promising material for Si-based long wavelength photodetectors and electronic devices国家自然科学基金(批准号:60676027,50672079,60336010);; 福建省重点科技项目(批准号:2006H0036);; 教育部回国留学人员启动基金资助项目~

UHV/CVD法生长硅基低位错密度厚锗外延层

采用超高真空化学气相淀积系统,以高纯Si_2H_6和GeH_4作为生长气源,用低温缓冲层技术在Si（001）衬底上成功生长出厚的纯Ge外延层.对Si衬底上外延的纯Ge层用反射式高能电子衍射仪、原子力显微镜、X射线双晶衍射曲线和Ra-man谱进行了表征.结果表明在Si基上生长的约550nm厚的Ge外延层,表面粗糙度小于1nm,XRD双晶衍射曲线和Ra-man谱Ge-Ge模半高宽分别为530″和5.5cm~(-1),具有良好的结晶质量.位错腐蚀结果显示线位错密度小于5×105cm~(-2).可用于制备Si基长波长集成光电探测器和Si基高速电子器件