Objectif GAAS THIN FILM SOLAR CELLS HAVE SHOWN THEIR POTENTIAL FOR HIGH EFFICIENCY ABOVE 10%. THEY ARE CONSIDERED FOR COMPONENTS IN TANDEM SOLAR CELLS. PROBLEMS HAVE BEEN FOUND REGARDING DEPOSITION TEMPERATURES CRYSTALLITE CONFIGURATION AND GRAIN BOUNDARIES. IT IS THE AIM OF THE PROPOSED WORK TO DEMONSTRATE THAT A NEW, ION-ASSISTED DEPOSITION PROCESS, "ION CLUSTER BEAM" DEPOSITION (ICB) CAN LEAD TO SIGNIFICANTLY IMPROVED GAAS THIN FILM SOLAR CELLS AT LOWER SUBSTRATE TEMPERATURES THAN NEEDED IN THE PAST. IN ICB DEPOSITION THE MATERIAL, E.G. GA AND AS IS TRANSPORTED TOWARDS THE SUBSTRATE IN THE FORM OF SMALL CLUSTERS CONTAINING APPROX. 100 ATOMS, WHICH ARE CHARGED BY ELECTRON BEAM AND ACCELARATED TOWARDS THE SUBSTRATE BY AN ELECTRIC FIELD. THE KINETIC ENERGY OF THE ARRIVING CLUSTERS, DECOMPOSING INTO ATOMS, REPRESENTS A "VIRTUAL TEMPERATURE", FACILITATING REACTION AND CRYSTALLITE GROWTH. GAAS DEPOSITION TECHNOLOGIES RECENTLY HAVE FOUND INCREASED INTEREST UNDER THE AIM OF MONOLITHICALLY INTEGRATING GAAS AND SI TECHNOLOGIES FOR ELECTRONIC AND OPTOELECTRONIC APPLICATIONS. THIS WILL ALSO INFLUENCE GAAS THIN FILM SOLAR CELL DEVELOPMENT EFFORTS. THE POTENTIAL FOR ACHIEVING ABOVE 10% EFFICIENCY FOR POLYCRYSTALLINE FILMS, CLOSE TO 20% FRO FILMS ON SI AND GE AND WELL ABOVE 20% FRO FILMS ON BULK GAAS HAS RECENTLY BEEN DEMONSTRATED. IT IS THE AIM OF THE PROJECT TO DEPOSIT GAAS FILMS BY MEANS OF THE "IONIZED CLUSTER BEAM" DEPOSITION PROCESS, AND TO OPTIMIZE THEM INSOFAR, THAT FILMS SUITED FOR SOLAR CELL APPLICATION CAN BE OBTAINED AT LOWEST POSSIBLE SUBSTRATE TEMPERATURES. THE PROCESS HAS BEEN DEFINED SO, THAT IN THE FIRST PHASE GA WILL BE DEPOSITED BY ICB AND AS WILL BE COEVAPORATED AS ELEMENT. THE COMPONENTS FOR THE PROCESS HAVE BEEN PURCHASED, DEVELOPED AND BUILT. AFTER INDIVIDUAL TESTS THEY HAVE BEEN INSTALLED WITHIN THE VACUUM VESSEL. GAAS FILMS HAVE BEEN DEPOSITED ONTO COMMERCIAL GAAS WAFERS AT TEMPERATURES OF 580 C UNDER EXCESS AS-FLUX AT A DEPOSTITION RATE OF 2A/S. MAIN PARAMETER TO BE VARIED HAS BEEN THE ACCELERATION POTENTIAL FOR THE IONIZED CLUSTERS. FIRST OPTIMISATION STEPS HAVE LED TO EPITAXIAL FILMS ON GAAS HAVING P-DOPING LEVELS AS LOW AS 10E12CM-E3 AND HOLE MOBILITIES OF UP TO 250CME2V-1S-1, AS DETERMINED FROM FILMS GROWN ON HIGH-RESISTIVITY WAFERS. Champ scientifique agricultural sciencesagriculture, forestry, and fisheriesagriculturegrains and oilseedsengineering and technologymaterials engineeringcoating and films Programme(s) FP1-ENNONUC 3C - Research and development programme (EEC) in the field of Non-Nuclear Energy, 1985-1988 Thème(s) Data not available Appel à propositions Data not available Régime de financement CSC - Cost-sharing contracts Coordinateur Battelle-Institut eV Contribution de l’UE Aucune donnée Adresse Am Römerhof 35 60486 Frankfurt am Main Allemagne Voir sur la carte Coût total Aucune donnée
