Verfahren zum Herstellung von grossflaechigen Siliziumkristallkoerpern fuer Solarzellen

DE 3536743 A UPAB: 19930922 Silicon-powder with a grainsize of not more than 100 microns is poured into a flat container (3) which has a surface of Si or a Si-cpd. and a size consistent with that of the Si-sheet to be produced. A layer several grain-sizes thick is formed and then densified by compression. The layer is then sintered by heating for about 1 minute at 1350-1400 deg.C resulting in a layer of 300-1000 micron thickness which is self-supporting. The heating is single-sided and uses radiation by halogen lamps of at least 6 KW in an ambient of Argon. The lamp is fitted inside a reflector with an elliptical cross-section to focus the light in a narrow strip on the substrate. This is followed by another heat-treatment in which at least half of the thickness of the foil is molten where it is irradiated and recrystallises when it moves out of this area. In a third heat-treatment the other part of the foil is treated similarly and grains are formed which equal the thickness of the foil in size. This process can be carried out on a moving belt principle using 3 heat sources with reflectors if the third source is placed below the foil. USE/ADVANTAGE - The process does not introduce contamination like current processes do because no binder is used. The sintering process is carried out in a reactor with cold walls while the foil is self-supporting. The grain growth is homogeneous, producing large grains. 6/