Thermal and electrical conductance and thermopower at the nanoscale

纳米尺度的热导、电导和热电

• 批准号: 120933829
• 负责人: Professor Dr. Gianaurelio Cuniberti
• 金额: --
• 依托单位: Professur für Materialwissenschaft und Nanotechnik
• 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 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/120933829?language=en
• 关键词: Thermal; electrical; conductance; thermopower; nanoscale

In the previous funding phase, we have set the basis for a detailed study of the electrical and thermal transport properties of hybrid heterostructures consisting of semiconducting materials functionalized by organic molecules. Experimentally, novel methodologies were developed. A new self-assembled monolayers (SAM) soft-contacting method was established which allowed us to obtain the first reliable transport measurements of SAMs contacted by two semiconducting electrodes. We identified different low temperature transport regimes of alkane chains with varying lengths. We also succeeded to "roll-up and press-back" superlattice stacks of different material compositions, mainly semiconducting and metal layers. Preliminary results of the cross-sectional electrical as well as thermal conductivity were obtained using thermoreflectance and local 3ω measurements. In the second period, we will focus on (i) the preparation of micro-patterned contacts to the mesas in order to obtain a complete figure of merit, and (ii) the incorporation of suitable molecular layers with tailored electrical and thermal properties, which will be identified in close cooperation with the theoretical partners. From the modeling point of view, our work progressed in two directions: (a) development of efficient computational methodologies to treat, on a first principle basis, thermal transport in large (experimentally relevant) systems and (b) application of first principle methods combined with Green function techniques to investigate the thermoelectric properties of silicon-molecule-silicon junctions. Hereby a special focus was to demonstrate the possibility of tuning the thermopower of the junction via tailored modifications of the chemical composition of the molecules. In the second funding period, we will apply these methodologies, in close cooperation with the experimental partners, to study (i) electrical and thermal transport in hybrid heterostructures consisting of semiconductor electrodes and pre-defined molecular SAMs, and (ii) to develop a methodology to compute the relevant quantities determining the thermoelectric figure of merit on an atomistic level.

在之前的资助阶段，我们已经为详细研究由有机分子功能化的半导体材料组成的混合异质结构的电和热输运性质奠定了基础。在实验上，开发了新的方法。建立了一种新的自组装单分子膜（SAM）软接触方法，使我们能够获得第一个可靠的输运测量的SAM由两个半导体电极接触。我们确定了不同长度的烷烃链的不同低温输运制度。我们还成功地“卷起和压回”不同材料成分的超晶格堆叠，主要是半导体和金属层。使用热反射率和局部3ω测量获得了横截面电导率和热导率的初步结果。在第二阶段，我们将重点放在（i）微图案接触台面的制备，以获得一个完整的品质因数，以及（ii）合适的分子层与定制的电气和热性能，这将被确定在密切合作的理论合作伙伴。从建模的角度来看，我们的工作进展在两个方向：（a）开发有效的计算方法来治疗，在第一原理的基础上，在大型（实验相关）系统的热输运和（B）应用第一原理方法结合绿色函数技术，以调查硅分子硅结的热电性能。因此，一个特别的重点是通过调整分子的化学组成的修改来证明调谐结的热电势的可能性。在第二个资助期内，我们将与实验合作伙伴密切合作，应用这些方法来研究（i）由半导体电极和预定义分子自组装膜组成的混合异质结构中的电和热输运，以及（ii）开发一种方法来计算在原子水平上确定热电优值的相关量。