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Photoemission of spinpolarized electrons from strained GaAsP |
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| Authors: | P Drescher H G Andresen K Aulenbacher J Bermuth Th Dombol H Fischerz H Euteneuer N N Faleev M S Galaktionov D v Harrach P Hartmann J Hoffmann P Jennewein K H Kaiser S Köbis O V Kovalenkov H J Kreide J Langbeine Y A Mamaev Ch Nachtigall M Petri S Plützer E Reicherte M Schemies H -J Schöpe K -H Steffens M Steigerwald A V Subashiev H Trautner D A Vinokurov Y P Yashin B S Yavich |
| Institution: | (1) Institut für Kernphysik, Joh. Gutenberg Universität, 55099 Mainz, Germany;(2) Institut für Physik, Joh. Gutenberg Universität, 55099 Mainz, Germany;(3) Division of Experimental Physics, State Technical University, 195251 St. Petersburg, Russia;(4) A. F. Ioffe Physico-Technical Institute, 194021 St. Petersburg, Russia |
| Abstract: | Strained layer GaAs.95P.05 photo cathodes are presented, which emit electron beams spinpolarized to a degree of P = 75% typically. Quantum yields around QE = 0.4% are observed routinely. The figure of merit P2 × QE = 2.3 × 10–3 is comparable to that of the best strained layer cathodes reported in literature. The optimum wavelength of irradiating light around 830 nm is in convenient reach of Ti:sapphire lasers or diode lasers respectively. The cathodes are produced using MOCVD-techniques. A GaAs.55P.45-GaAs.85P.15 superlattice structure prevents the migration of dislocations from the substrate and bottom layers to the strained overlayer. The surface is protected by an arsenic layer so that no chemical cleaning is necessary before installation into vacuum. The source of polarized electrons attached to the Mainz race track microtron MAMI works with such cathodes now. More than 1000 hours beamtime have been performed successfully. |
| Keywords: | 79 60 |
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