Department of Materials Science and nanoEngineering, Rice University, Houston, Texas 77005, USA.
Nanoscale. 2015 May 21;7(19):8776-81. doi: 10.1039/c5nr01892g.
Combining density functional theory and the nonequilibrium Green's function method, we investigate the thermoelectric properties of thin GaAs nanowires (NWs). After identifying the most stable structures for GaAs NWs, either in wurtzite (wz) or zinc blende (zb) stacking, we present a systematic analysis on the thermoelectric properties of these NWs and their dependence on stacking type (wz or zb), size of NWs, and temperature. Although bulk GaAs is a well-known poor thermoelectric material, the thermoelectric figure of merit, ZT, is significantly enhanced in thin GaAs NWs. Typically, the room temperature ZT of a 1.1 nm-diameter GaAs NW reaches as high as 1.34, exhibiting more than 100-fold improvement over the bulk counterpart, which is attributed to both the reduced thermal conduction and enhanced power factor in thin NWs. Adopting their unique electronic characteristics, further enhancement is possible through surface engineering, for example, the introduction of surface roughness or dopants.
我们采用密度泛函理论和非平衡格林函数方法研究了 GaAs 纳米线的热电性质。在确定了纤锌矿（wz）或闪锌矿（zb）堆垛结构的 GaAs 纳米线最稳定的结构之后，我们对这些纳米线的热电性质及其对堆垛类型（wz 或 zb）、纳米线尺寸和温度的依赖性进行了系统的分析。尽管体 GaAs 是一种众所周知的较差的热电材料，但在 GaAs 纳米线中，热电优值 ZT 得到了显著提高。通常，1.1nm 直径 GaAs 纳米线在室温下的 ZT 高达 1.34，比体材料提高了 100 多倍，这归因于纳米线中热传导的降低和功率因子的增强。通过表面工程（例如引入表面粗糙度或掺杂剂）利用其独特的电子特性，可以进一步提高性能。
