Thermopower enhancement by fractional layer control in 2D oxide superlattices

TL;DR

This study demonstrates that fractional layer control in 2D oxide superlattices significantly enhances thermoelectric properties, achieving record thermopower and power factor values by tuning carrier density.

Contribution

It introduces a novel method of directly tuning 2D carrier density in oxide superlattices, leading to unprecedented thermoelectric performance improvements.

Findings

Achieved thermopower of 408 μV/K in 2D oxide superlattices.

Realized a power factor of 117 μW/cm·K², among the highest for transition metal oxides.

Attribution of enhanced thermoelectric properties to anisotropic band structure.

Abstract

We have investigated two-dimensional thermoelectric properties in transition metal oxide heterostructures. In particular, we adopted an unprecedented approach to direct tuning of the 2D carrier density using fractionally {\delta}-doped oxide superlattices. By artificially controlling the carrier density in the 2D electron gas that emerges at a LaxSr1-xTiO3 {\delta}-doped layer, we demonstrate that a thermopower as large as 408 {\mu}V K-1 can be reached. This approach also yielded a power factor of the 2D carriers 117 {\mu}Wcm-1K-2, which is one of the largest reported values from transition metal oxide based materials. The promising result can be attributed to the anisotropic band structure in the 2D system, indicating that {\delta}-doped oxide superlattices can be a good candidate for advanced thermoelectrics.