Nanostructured electrodes for thermionic and thermotunnel devices

Abstract

Recently, distinctive quantum features have been studied in the area of ridged quantum wells (RQWs). 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, composed 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 WF. 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.