# US 6,294,726 B1 · Silicon with structured oxygen doping, its production and use > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,294,726 B1 - Document ID: US6294726B1 - Status: Granted - Kind: B1 - Application number: 09/591,518 - Filed: 2000-06-09 - Granted: 2001-09-25 - Earliest claimed: 1999-06-17 - Assignees: Bayer Aktiengesellschaft - Inventors: Christian Hässler; Hans-Ulrich Höfs; Wolfgang Koch; Siegfried Thurm; Otwin Breitenstein - Web page: https://patentgrep.com/patent/US6294726B1 ## CPC - C30B 29/06: Silicon - C30B 15/007: {Pulling on a substrate} - C30B 15/206: {the thermal history of growing the ingot} - C30B 15/34: Edge-defined film-fed crystal-growth using dies or slits - H10F 71/00: Manufacture or treatment of devices covered by this subclass (patterning processes to connect thin photovoltaic cells in integrated devices, or assemblies of multiple devices, having photovoltaic cells H10F19/33; manufacture or treatment of encapsulations or containers for integrated devices, or assemblies of multiple devices, having photovoltaic cells H10F19/80; manufacture or treatment of integrated devices, or assemblies of multiple devices, comprising at least one element in which radiation controls the flow of current H10F39/00) - H10F 71/1221: {comprising polycrystalline silicon} - Y02E 10/546: Polycrystalline silicon PV cells - Y02E 10/547: Monocrystalline silicon PV cells - Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product - C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## 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. ## Claims ### Claim 1 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. ### Claim 2 (depends on 1) The silicon composition of claim 1, wherein at least 25% of the oxygen contained therein is in the form of silicon/oxygen precipitations. ### Claim 3 (depends on 2) The silicon composition of claim 2, wherein the silicon/oxygen precipitations are concentrated in the area of grain boundaries and dislocations. ### Claim 4 (depends on 1) The silicon composition of claim 1, wherein the silicon composition is p-doped. ### Claim 5 (depends on 1) The silicon composition of claim 1, wherein the silicon composition is n-doped. ### Claim 6 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. ### Claim 7 (depends on 6) The process of claim 6, wherein the step of substantially saturating the molten silicon with oxygen comprises the step of treating the molten silicon with an oxygen-containing gas before or during crystallization of silicon. ### Claim 8 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. ### Claim 9 (depends on 8) The process of claim 8, wherein the step of substantially saturating the molten silicon comprises the step of treating the molten silicon with an oxygen-containing gas before or during crystallization of silicon. ### Claim 10 (depends on 8) The process of claim 8, wherein the silicon is heated at a temperature of 500° C. to 1250° C. for a period of one minute to ten hours, wherein the temperature, within the indicated range, is kept constant or varied, and wherein the temperature exceeds 950° C. for at least one minute. ### Claim 11 (depends on 8) The process of claim 8, wherein the silicon is heated at a temperature of 800° C. to 1150° C. for a period of one minute to ten hours, wherein the temperature, within the indicated range, is kept constant or varied, and wherein the temperature exceeds 950° C. for at least one minute. ### Claim 12 (depends on 8) The process of claim 8, wherein the silicon is produced using a film-drawing or a film-casting process. ### Claim 13 (depends on 8) The process of claim 8, wherein the silicon composition is produced using a Ribbon Growth on Substrate process. ### Claim 14 (depends on 1) The silicon composition of claim 1, wherein the composition is a solar cell. ### Claim 15 (depends on 1) The composition of claim 1, wherein the silicon composition is a p-doped n+p-solar cell. ### Claim 16 (depends on 1) The composition of claim 1, wherein the composition is a n-doped p+n-solar cell.