Thermoelectric transport in strained Si and Si/Ge heterostructures

Abstract

The anisotropic thermoelectric transport properties of bulk silicon strained in [111]-direction were studied by detailed first-principles calculations focussing on a possible enhancement of the power factor. Electron as well as hole doping were examined in a broad doping and temperature range. At low temperature and low doping an enhancement of the power factor was obtained for compressive and tensile strain in the electron-doped case and for compressive strain in the hole-doped case. For the thermoelectrically more important high temperature and high doping regime a slight enhancement of the power factor was only found under small compressive strain with the power factor overall being robust against applied strain. To extend our findings the anisotropic thermoelectric transport of an [111]-oriented Si/Ge superlattice was investigated. Here, the cross-plane power factor under hole-doping was drastically suppressed due to quantum-well effects, while under electron-doping an enhanced power factor was found. With that, we state a figure of merit of ZT$=0.2$ and ZT$=1.4$ at $T=\unit[300]{K}$ and $T=\unit[900]{K}$ for the electron-doped [111]-oriented Si/Ge superlattice. All results are discussed in terms of band structure features.

References in corpus (6)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Model for the on-site matrix elements of the tight-binding hamiltonian of a strained crystal: Application to silicon, germanium and their alloys
• Influence of strain on anisotropic thermoelectric transport of Bi${}_2$Te${}_3$ and Sb${}_2$Te${}_3$
• Huge Thermoelectric Power Factor: FeSb2 versus FeAs2 and RuSb2
• Effect of strain on the thermoelectric properties of silicon: An ab initio study
• $B{i}_{2}T{e}_3$: Implications of the rhombohedral k-space texture on the evaluation of the in-plane/out-of-plane conductivity anisotropy

Cited by in corpus (6)

• First-Principles Prediction of Electronic Transport in Experimental Semiconductor Heterostructures via Physics-Based Machine Learning
• Enhancement of the electronic thermoelectric properties of bulk strained silicon-germanium alloys using the scattering relaxation times from first principles
• Lorenz function of Bi${}_2$Te${}_3$/Sb${}_2$Te${}_3$ superlattices
• Theoretical Prediction of Enhanced Thermopower in n-doped Si/Ge Superlattices using Effective Mass Approximation
• Significant reduction in semiconductor interface resistance via interfacial atomic mixing
• Modulation of Semiconductor Superlattice Thermopower Through Symmetry and Strain