Comparison of CsBr and KBr coated Cu photocathodes. Effects of laser irradiation and work function changes

Journal Article · Wed Feb 20 04:00:00 EST 2013 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4793214· OSTI ID:1072853

He, Weidong ^[1]; VilayurGanapathy, Subramanian ^[1]; Joly, Alan G. ^[1]; Droubay, Timothy C. ^[1]; Chambers, Scott A. ^[1]; Maldonado, Juan R. ^[2]; Hess, Wayne P. ^[1]

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1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2. Stanford Univ., CA (United States)

Thin films (7 nm layers) of CsBr and KBr were deposited on Cu(100) to investigate photoemission properties of these potential photocathode materials. After thin film deposition and prolonged laser ultraviolet (UV) irradiation (266 nm picosecond laser) photoemission quantum efficiency increases by factors of 26 and 77 for KBr/Cu(100) and CsBr/Cu(100) photocathodes, respectively. Immediately following thin film deposition, a decrease in work function is observed, compared to bare Cu, in both cases. Quantum efficiency enhancements are attributed to the decrease in photocathode work function, due to the deposition of alkali halide thin films, and photo-induced processes, that introduce defect states into the alkali halide bandgap, induced by UV laser irradiation. It is possible that alkali metal formation occurs during UV irradiation and that this further contributes to photoemission enhancement. Our results suggest that KBr, a relatively stable alkali-halide, has potential for photocathode applications.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1072853
• Report Number(s): PNNL-SA--92864; 47670
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 7 Vol. 102; ISSN 0003-6951
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
Environmental Molecular Sciences Laboratory