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

TL;DR

This paper demonstrates that integrating ridged quantum wells with top-layer junctions significantly enhances the thermoelectric figure of merit by increasing the Seebeck coefficient without affecting other transport properties.

Contribution

It introduces a novel system combining RQW with top-layer junctions that amplifies thermoelectric performance through temperature-dependent chemical potential modifications.

Findings

Seebeck coefficient S increases dramatically.

Thermoelectric figure of merit ZT improves by an order of magnitude.

Other transport coefficients remain unchanged.

Abstract

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.