Silicon with structured oxygen doping, its production and use
AssigneeBayer Aktiengesellschaft
InventorsChristian Hässler, Hans-Ulrich Höfs, Wolfgang Koch, Siegfried Thurm, Otwin Breitenstein
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Abstract
The present invention relates to silicon with a high oxygen content and, at the same time, a high density of crystal lattice dislocations, and to its production. This silicon may be used in photovoltaics. Solar cells which are based on the material according to the invention exhibit high levels of efficiency despite the high oxygen content.
Claims16
A silicon composition comprising a total oxygen content of 8×1017 atoms/cm3 to 1×1019 atoms/cm3 and a dislocation density of 1×105 cm−2 to 5×10 cm−2, and wherein the silicon is polycrystalline.
A process for producing a silicon composition with a total oxygen content of 8×1017 atoms/cm3 to 1×1019 atoms/cm3 and a dislocation density of 1×105 cm−2 to 5×107 cm−2;
- the process comprising substantially saturating with oxygen a molten silicon that is in contact with a member selected from the group consisting of silicon monoxide and silicon dioxide;
- wherein the dislocation density is set by means of the cooling rate of the silicon.
A process for producing a silicon composition with a total oxygen content of 8×1017 atoms/cm3 to 1×1019 atoms/cm3, a dislocation density of 1×105 cm−2 to 5×107 cm−2, and at least 25% of the oxygen present in the form of silicon/oxygen precipitations which are concentrated in the area of grain boundaries and dislocations;
- the process comprising substantially saturating with oxygen a molten silicon that is in contact with a member selected from the group consisting of silicon monoxide and silicon dioxide;
- wherein the dislocation density is set by means of the cooling rate of the silicon, and wherein the proportion of the total oxygen content made up of silicon/oxygen precipitations and the concentration thereof in the area of grain boundaries and dislocations is achieved by heat treatment of the silicon.
Dependencies are inferred from the claim text.