title: Photon-enhanced thermionic emission from heterostructures with low interface recombination.
abstract: Photon-enhanced thermionic emission is a method of solar-energy conversion that promises to combine photon and thermal processes into a single mechanism, overcoming fundamental limits on the efficiency of photovoltaic cells. Photon-enhanced thermionic emission relies on vacuum emission of photoexcited electrons that are in thermal equilibrium with a semiconductor lattice, avoiding challenging non-equilibrium requirements and exotic material properties. However, although previous work demonstrated the photon-enhanced thermionic emission effect, efficiency has until now remained very low. Here we describe electron-emission measurements on a GaAs/AlGaAs heterostructure that introduces an internal interface, decoupling the basic physics of photon-enhanced thermionic emission from the vacuum emission process. Quantum efficiencies are dramatically higher than in previous experiments because of low interface recombination and are projected to increase another order of magnitude with more stable, low work-function coatings. The results highlight the effectiveness of the photon-enhanced thermionic emission process and demonstrate that efficient photon-enhanced thermionic emission is achievable, a key step towards realistic photon-enhanced thermionic emission based energy conversion.
authors.affiliation: Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Schwede
authors.forename: T
authors.initials: T
authors.lastname: Sarmiento
authors.forename: V K
authors.initials: VK
authors.lastname: Narasimhan
authors.forename: S J
authors.initials: SJ
authors.lastname: Rosenthal
authors.forename: D C
authors.initials: DC
authors.lastname: Riley
authors.forename: F
authors.initials: F
authors.lastname: Schmitt
authors.forename: I
authors.initials: I
authors.lastname: Bargatin
authors.forename: K
authors.initials: K
authors.lastname: Sahasrabuddhe
authors.forename: R T
authors.initials: RT
authors.lastname: Howe
authors.forename: J S
authors.initials: JS
authors.lastname: Harris
authors.forename: N A
authors.initials: NA
authors.lastname: Melosh
authors.forename: Z-X
authors.initials: ZX
authors.lastname: Shen