Theory of thermoelectric power factor in quantum well and quantum wire superlattices
Theory of thermoelectric power factor in quantum well and quantum wire superlattices
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DOI：
10.1103/physrevb.64.045324
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发表时间：
2001-07
影响因子：
3.7
通讯作者：
D. Broido;T. Reinecke
中科院分区：
文献类型：
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作者：
D. Broido;T. Reinecke
利用(i)、（ii）中载流子-声子散射的多子带非弹性玻尔兹曼方程中的全超晶格电子带结构，对量子阱和量子线超晶格中的热电输运进行了计算。输运方向取在量子阱平面内和沿量子线方向。证明了这两个特征是定量处理超晶格系统中功率因数P所必需的。给出了PbTe和GaAs量子阱和量子线超晶格的结果，包括P对生长方向和电位偏移的依赖。对于量子阱和量子线超晶格，发现P对势偏置v0的依赖比先前基于载流子散射的恒定弛豫时间近似的工作在质量上弱。这些对v0的依赖性较弱主要是由于电子-声子散射率在约束后的增强。这些结果给出了限制对P的影响的不同图景，例如，在超晶格中增加限制并不会导致P显著增加，而独立结构，如独立量子线，可能对热电应用特别有吸引力。
Calculations are presented for thermoelectric transport in quantum well and quantum wire superlattices, using (i), the full superlattice electronic band structure in (ii) a multisubband inelastic Boltzmann equation for carrier-phonon scattering. The transport direction is taken to be in the quantum well planes and along quantum wires. It is demonstrated that these two features are needed to give a quantitative treatment of the power factor P in superlattice systems. Results are given for PbTe and for GaAs quantum well and quantum wire superlattices, including the dependence of P on growth direction and on potential offset. For both quantum well and quantum wire superlattices, the dependence of P on potential offset V 0 is found to be qualitatively weaker than in previous work based on the constant relaxation time approximation for carrier scattering. These weaker dependences on V 0 are traced mainly to the enhancement of the electron-phonon scattering rates upon confinement. These results give a different picture of the effects of confinement on P suggesting, for example, that increased confinement in superlattices does not lead to significantly higher P and that free-standing structures, such as free-standing quantum wires, may be particularly attractive for thermoelectric applications.