Tailoring low energy electron absorption via surface nano-engineering of cesiated chromium films

Fernandes Cauduro, Andre L.; Hess, Lucas H.; Ogletree, D. Frank; Schwede, Jared W.; Schmid, Andreas K.

doi:10.1063/1.5099115

Tailoring low energy electron absorption via surface nano-engineering of cesiated chromium films

Journal Article · Tue Aug 13 00:00:00 EDT 2019 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.5099115· OSTI ID:1605692

^[1]; Hess, Lucas H. ^[2]; ^[1]; Schwede, Jared W. ^[3]; Schmid, Andreas K. ^[1]

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Spark Thermionics, Inc., Berkeley, CA (United States)
Spark Thermionics, Inc., Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Here, we demonstrate that improved low energy electron absorption is achieved by suppressing the crystallinity of chromium thin-films grown on W[110], which points to a promising route for achieving highly efficient thermionic energy converters. Using low energy electron microscopy (LEEM) and in situ film growth, we show that substrate temperature control permits well-controlled fabrication of either epitaxial Cr[110] films or nanocrystalline Cr layers. We show that the work function of cesium saturated nanocrystalline Cr thin-films is ~0.20 eV lower than that of epitaxial Cr[110] films. Our LEEM measurements of absorbed and reflected currents as a function of electron energy demonstrate that nanocrystallinity of cesiated chromium films results in 96% electron absorption in the range up to 1 eV above the work function, compared to just 79% absorption in cesiated crystalline Cr[110] films. These results point to metal films with suppressed crystallinity as an economical and scalable means to synthesize nanoengineered surfaces with optimized properties for next generation anode materials in high performance thermionic energy converters.

View Accepted Manuscript (DOE)

Research Organization:: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Organization:: USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)

Grant/Contract Number:: AC02-05CH11231; AR0000664

OSTI ID:: 1605692

Alternate ID(s):: OSTI ID: 1557025

Journal Information:: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 7 Vol. 115; ISSN 0003-6951

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

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