Silicon-based thermoelectric nanosystems

硅基热电纳米系统

• 批准号: 121821990
• 负责人: Professor Dr. Karl Brunner
• 金额: --
• 依托单位: Institut für Halbleitertechnik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/121821990?language=en
• 关键词: Silicon; based; thermoelectric; nanosystems

Thermoelectric (TE) generators directly mounted into the exhaust gas return (EGR) cooler can help to harvest a portion of the huge amount of day-to-day wasted heat. They have to endure constant and cycling temperature loading up to around 500°C, which cannot be fulfilled by Bi2Te3 -based TE material but by silicon. Bulk silicon, however, has a low figure of merit (ZT ~ 0.01) owing to high thermal conductivity. In the first funding period we found that by patterning silicon into nanowires of ~ 200 nm in diameter in combination with a rough nanorod surface thermal conductivity was strongly reduced corresponding to ZT ~ 0.14 at conservative assumptions for the Seebeck coefficient and the resistivity. Further reduction of thermal conductivity and thus improvement towards ZT > 1 resulting in efficiencies necessary for a practical harvesting device (10 to 20 %) is planned for the second funding period which shall be achieved by 1) enhancing the surface-to-volume ratio and thus phonon surface scattering via further reducing the nanowire diameter to < 100 nm or by adding an inner surface (Si nanotube), 2) engineering the nanowire surface for more efficient phonon roughness scattering, 3) integration of multilayer structures into silicon nanowires (Si/SiGe, Si/SiOx, 28Si/29Si) to exploit the effect of heterointerfaces, boundaries, alloys and isotopes on phonon scattering.

直接安装在废气回流 (EGR) 冷却器中的热电 (TE) 发电机可以帮助收集日常大量废热的一部分。它们必须承受高达 500°C 左右的恒定和循环温度负载，而基于 Bi2Te3 的 TE 材料无法满足这一要求，而只能通过硅。然而，由于高导热性，块状硅的品质因数较低（ZT ~ 0.01）。在第一个资助期间，我们发现，通过将硅图案化为直径约 200 nm 的纳米线，并结合粗糙的纳米棒表面，热导率大大降低，在塞贝克系数和电阻率的保守假设下，热导率对应于 ZT ~ 0.14。计划在第二个资助期进一步降低热导率，从而提高 ZT > 1，从而提高实际收集装置所需的效率（10% 至 20%），这应通过以下方式实现：1) 通过进一步将纳米线直径减小到 < 100 nm 或通过添加内表面（硅纳米管）来提高表面与体积比，从而提高声子表面散射，2) 对纳米线进行工程设计 表面以获得更有效的声子粗糙度散射，3）将多层结构集成到硅纳米线（Si/SiGe、Si/SiOx、28Si/29Si）中，以利用异质界面、边界、合金和同位素对声子散射的影响。