硅基一维异质纳米热电材料结构与性能调控及其器件基础研究

近年来，随纳米技术飞速发展，在原子和分子层面上设计、制备新材料以大幅提高其热电性能成为可能。因此，以材料纳米化为主体的热电材料与器件的研究成为热点。本课题针对此热点问题，以提高硅基异质纳米材料和器件的热电性能为目标，通过对硅基一维异质材料的微纳结构进行调控，利用多波段声子散射效应，并结合能带工程及电导调制等技术，在抑制热输运的同时，提高其功率因子，从而解决热电材料热导率、电导率及赛贝克系数之间相互制约这一关键问题，最终提高其热电优值。通过本课题的研究，重点解决硅基一维异质外延过程中的应力调控及热力学控制问题，实现硅基核壳纳米线及超晶格纳米线的可控制备；发展纳米线阵列材料横向转移技术用于纳米线阵列热电器件制备及表征的方法。通过利用纳米线管状二维电子气、材料能带结构调控等创新方案，实现热、电协同输运，制备出高效硅基热电材料，为发展廉价硅基热电器件奠定基础。

With the quick development of nanotechnology, it is possible to greatly enhance the thermoelectric performance of materials by design and fabrication of new materials on the atomic and molecular level. Researches on thermoelectric materials and devices have become an active research area due to the rapid development of nanotechnology. This project aims to improve the thermoelectric performance of Si-based 1D nanomaterials by using multi-phonon scattering effect at interfaces, the energy-band engineering and conduction modulation. It is expected to suppress the phonon-related thermal conductivity, increase the power factor of thermoelectric materials and eventually break the correlation between thermal conductivity, electric conductivity and Seebeck coefficient. The growth mechanisms of 1D Si based heterostructures will also be analyzed and properly understood in order to realize their controllable growth. We will explore ways to effectively control the mismatched-induced stress and seek the possibility of thermodynamic-control of the epitaxial shell structures. The project will emphasize on the development an easy and efficient way to characteristize the thermoelectric performances of nanowire arrays by applying the technique of nanowire transferring onto the insulated substrate. By using the two dimensional electron(hole) gas effect and the band gap enginnering technique,we try to realize the trade off between electric-conductivity and therm-oconductivity. Hopefully this work could lay a sound foundation for developing the high efficient Si-based thermoelectric materials and devices.