Nanostructured electrodes for thermionic and thermo-tunneling devices

TL;DR

This paper explores how nanostructured ridged quantum wells can significantly lower work functions of electrodes, enhancing thermionic and thermotunnel device performance at room temperature.

Contribution

It introduces a method to reduce work function using ridged quantum wells on various substrates, with calculations showing substantial WF reduction for different material combinations.

Findings

WF can be dramatically reduced with ridged quantum well structures.

Wide band gap semiconductors are effective substrates for WF reduction.

Low Fermi energy metals are preferable on metal substrates.

Abstract

Recently, new quantum features have been studied in the area of ridged quantum wells (RQW). Periodic ridges on the surface of the quantum well layer impose additional boundary conditions on the electron wave function and reduce the quantum state density. Electrons, rejected from forbidden quantum states, have to occupy the states with higher energy. As a result, Fermi energy in RQW increases and work function (WF) decreases. We investigate low WF electrode, com-posed from a metal RQW layer and a base substrate. The substrate material was selected so that electrons were confined to the RQW. The WF value depends on ridge geometry and electron confinement. We calculate WF in the metal RQW films grown both on a semiconductor and metal substrates. In the case of semiconductor substrate, wide band gap materials are preferable as they allow more reduction in RQW work function. In the case of metal substrate, low Fermi energy materials are preferable. For most material pairs, the WF was reduced dramatically. Such structures, can serve as electrodes for room temperature thermionic and thermotunnel energy converters and coolers.