Functionally Graded Ge1-xSix Thermoelectrics by Simultaneous Band Gap and Carrier Density Engineering
Functionally Graded Ge1-xSix Thermoelectrics by Simultaneous Band Gap and Carrier Density Engineering
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DOI：
10.1021/cm502042e
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发表时间：
2014-09-09
影响因子：
8.6
通讯作者：
Iversen, Bo B.
中科院分区：
文献类型：
--
作者：
Hedegaard, Ellen M. J.;Johnsen, Simon;Iversen, Bo B.
利用晶体生长技术固有的材料梯度，硼掺杂的Ge 1xSix（x = 0至类似于0.25）样品的带隙和载流子浓度的梯度已通过直拉法制备。沿着Ge 1xSix样品的长度x连续变化，从而引起带隙从0.87到0.65 eV的变化。类似地，硼含量的梯度导致载流子密度沿着样品连续变化。这导致样品在与热电性能相关的几个材料参数中分级。因此，本研究展示了一个一步的方法制备梯度的载流子浓度和带隙的热电。通过掺杂剂和材料系统的仔细匹配，证明了掺杂剂和带隙的梯度如何协同工作，并相互增强热电性能。
Exploiting the material gradients inherent to crystal growth techniques, boron doped Ge1xSix (x = 0 to similar to 0.25) samples graded in both band gap and carrier concentration have been prepared by the Czochralski method. Along the length of the Ge1xSix samples x changes continuously, giving rise to changes in the band gap from 0.87 to 0.65 eV. Similarly, gradients in the boron content results in continuous carrier density changes along the sample. This results in samples graded in several material parameters relevant to thermoelectric performance. The present study thereby demonstrates a one-step method for preparing thermoelectrics graded in both carrier concentration and band gap. By careful matching of dopant and material system, it is demonstrated how the gradient in dopant and band gap can work in synergy and mutually enhance the thermoelectric performance over the individual contributions.