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arXiv 0905.3525cond-mat.mes-hallcond-mat.mtrl-sci
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脊量子阱中热电优值的大幅度提高

Large enhancement of the thermoelectric figure of merit in a ridged quantum well

Avto Tavkhelidze

摘要:

近年来,人们在脊量子阱(RQW)中观察到并研究了新的量子特性。量子阱层表面上的周期性脊对电子波函数施加了附加的边界条件并降低了量子态密度。结果,RQW的化学势增加,并成为脊高度依赖。在这里,我们提出的系统包括RQW和附加层的顶部的脊形成周期性系列的p+-n+结(或金属-n+结)。在这样的系统中,电荷耗尽区在脊内发展,有效脊高度减小,成为温度T的较强函数。因此,化学势的T依赖性放大,塞贝克系数S增大。我们研究了脊上具有突变p ~+-n ~+结或金属-n ~+结的半导体RQW系统中的S。玻尔兹曼输运方程的基础上进行的分析表明,在这两种情况下,S显着增加。同时,其他输运系数不受结的影响。计算表明,相对于大块材料,热电优值ZT增加了一个数量级。

英文摘要:

Recently new quantum features were observed and studied in the ridged quantum wells (RQW). Periodic ridges on the surface of the quantum well layer impose additional boundary conditions on electron wave function and reduce quantum state density. As result, chemical potential of RQW increases and becomes the ridge height dependent. Here we propose system comprising of RQW and additional layer on the top of the ridges forming periodic series of p+-n+ junctions (or metal-n+ junctions). In such systems charge depletion region develops inside the ridges and effective ridge height reduces, becoming rather strong function of temperature T. Consequently, T dependence of chemical potential magnifies and Seebeck coefficient S increases. We investigate S in the system of semiconductor RQW having abrupt p+-n+ junctions or metal-n+ junctions on the top of the ridges. Analysis made on the basis of Boltzmann transport equations shows dramatic increase in S for both cases. At the same time other transport coefficients remain unaffected by the junctions. Calculations show one order of magnitude increase in thermoelectric figure of merit ZT relative to the bulk material.

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