高热电优值硅纳米线研究

项目名称： 高热电优值硅纳米线研究

项目编号： No.60876081

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 冯飞

作者单位： 中国科学院上海微系统与信息技术研究所

项目金额： 32万元

中文摘要： 热电材料未获大规模应用的主要原因在于材料的热电优值（ZT）不高或成本高，探寻具有高ZT、成本低且易于制备的材料成为研究者关注的焦点。硅是常用半导体材料，但其ZT较低。本项目围绕硅纳米线热电性能展开研究，主要内容包括：硅纳米线热电优值理论研究、制备技术研究以及热电性能实验研究。主要研究成果有：1.建立了硅纳米线热电优值的理论模型，确立了ZT与掺杂浓度、结构参数的关系：硅纳米线特征尺寸≤0nm时，与体硅相比其热导降低了2个数量级；对理想半导体而言，当载流子浓度为7.71E18cm-3，ZT达最大值9.22E-3；满足上述两条件时ZT可接近1。2.完成了硅纳米线热电性能测试结构设计。3.通过掺杂工艺研究，在SOI埋层氧化硅上60nm的顶层硅中获得了1E19cm-3的掺杂浓度；基于各向异性腐蚀工艺制备出了最小线宽为5.56nm的硅纳米线。4.设计了合理的MEMS工艺流程，制备出了硅纳米线热电性能测试结构。5.搭建了热电性能测试平台。测试结果表明，硅纳米线ZT优于体硅，在200K时具有较大的塞贝克系数和ZT。上述研究表明硅纳米线有望成为一种具有较高性价比的热电材料。

中文关键词： 硅纳米线；热电优值；MEMS

英文摘要： The thermoelectric materials can not be widely applied because of low thermoelectric figure of merit ZT and high cost. Seeking thermoelectric materials with high ZT, low cost and easily fabrication becomes the focus of many researchers. Silicon is a standard semi-conductor material, but its ZT is low. The thermoelectric performance of silicon nanowires is studied in this project. The main study contents include: theoretical study on ZT of silicon nanowires; study on MEMS fabrication process of silicon nanowires; experimental study on the thermoelectric performance of silicon nanowires.The main achievements include: 1.The theoretical model of ZT of silicon nanowires is built, and functional relationships between ZT and doping concentration, structural parameters of silicon nanowires are confirmed: thermal conductivity of silicon nanowires with the feature size of 20nm or less is reduced by 2 orders of magnitude compared to bulk silicon; ZT reaches the maximum value 9.22E-3 for an ideal semiconductor with 7.71E18cm-3 doping concentration; ZT is close to 1 if the above-mentioned two conditions are met. 2. The optimization design of the testing structure of thermoelectric performance of silicon nanowire is completed. 3. 1E19cm-3 doping concentration in the 60nm top silicon layer above buried silicon oxide layer of SOI is obtained based on doping process study; the silicon nanowires with 5.56nm minimum line width are prepared by using the anisotropic etching process. 4. The test structure of thermoelectric performance of silicon nanowires is prepared by a reasonable MEMS process. 5. The testing platform of the thermoelectric performance is built. The test results show that ZT of silicon nanowires is superior to bulk silicon; the Seebeck coefficient and ZT are larger in 200K temperature. The study shows that silicon nanowires are expected to become a cost-effective thermoelectric material.

英文关键词： Silicon nanowires; Thermoelectric figure of merit; MEMS