Electric Field Thermopower Modulation of Two-Dimensional Electron Gas

Themopower $(S)$ is known as not only an important physical property for thermoelectric energy conversion but also a useful to understand electronic structures of materials since $\vert S\vert$ strongly depends on the energy derivative of the electronic DOS at around the Fermi energy. In case of bulk system, the slope of log $n$ vs. $S$ relation should be -ln $10\cdot k_{\mathrm{B}}\cdot e^{-1}(\equiv-198\mu \mathrm{VK}^{-1}\mathrm{decade}^{-1})$ since parabolic shaped $E-k$ relation at around the conduction band minimum is generally observed. Further, an enhanced $S$ can be observed by modifying the DOS in low-dimensional structures such as two-dimensional electron gas (2DEG). Here I review the electric field modulated $S$ of 2DEGs confined in the several transistors including SrTiO3, BaSnO3, and AlGaN/GaN heterointerfaces.