Abstract:
Semi-conductor wafers with thin and thicker regions at controlled locations may be for Photovoltaics. The interior may be less than 180 microns or thinner, to 50 microns, with a thicker portion, at 180-250 microns. Thin wafers have higher efficiency. A thicker perimeter provides handling strength. Thicker stripes, landings and islands are for metallization coupling. Wafers may be made directly from a melt upon a template with regions of different heat extraction propensity arranged to correspond to locations of relative thicknesses. Interstitial oxygen is less than 6×1017 atoms/cc, preferably less than 2×1017, total oxygen less than 8.75×1017 atoms/cc, preferably less than 5.25×1017. Thicker regions form adjacent template regions having relatively higher heat extraction propensity; thinner regions adjacent regions with lesser extraction propensity. Thicker template regions have higher extraction propensity. Functional materials upon the template also have differing extraction propensities.
Abstract:
A pressure differential can be applied across a mold sheet and a semiconductor (e.g. silicon) wafer (e.g. for solar cell) is formed thereon. Relaxation of the pressure differential can allow release of the wafer. The mold sheet may be cooler than the melt. Heat is extracted through the thickness of the forming wafer. The temperature of the solidifying body is substantially uniform across its width, resulting in low stresses and dislocation density and higher crystallographic quality. The mold sheet can allow flow of gas through it. The melt can be introduced to the sheet by: full area contact with the top of a melt; traversing a partial area contact of melt with the mold sheet, whether horizontal or vertical, or in between; and by dipping the mold into a melt. The grain size can be controlled by many means.
Abstract:
A pressure differential can be applied across a mold sheet and a semiconductor (e.g. silicon) wafer (e.g. for solar cell) is formed thereon. Relaxation of the pressure differential can allow release of the wafer. The mold sheet may be cooler than the melt. Heat is extracted through the thickness of the forming wafer. The temperature of the solidifying body is substantially uniform across its width, resulting in low stresses and dislocation density and higher crystallographic quality. The mold sheet can allow flow of gas through it. The melt can be introduced to the sheet by: full area contact with the top of a melt; traversing a partial area contact of melt with the mold sheet, whether horizontal or vertical, or in between; and by dipping the mold into a melt. The grain size can be controlled by many means.
Abstract:
A pressure differential is applied across a mold sheet and a semiconductor (e.g. silicon) wafer (e.g. for solar cell) is formed thereon. Relaxation of the pressure differential allows release of the wafer. The mold sheet may be cooler than the melt. Heat is extracted almost exclusively through the thickness of the forming wafer. The liquid and solid interface is substantially parallel to the mold sheet. The temperature of the solidifying body is substantially uniform across its width, resulting in low stresses and dislocation density and higher crystallographic quality. The mold sheet must allow flow of gas through it. The melt can be introduced to the sheet by: full area contact with the top of a melt; traversing a partial area contact of melt with the mold sheet, whether horizontal or vertical, or in between; and by dipping the mold into a melt. The grain size can be controlled by many means.
Abstract:
A pressure differential is applied across a mold sheet and a semiconductor (e.g. silicon) wafer (e.g. for solar cell) is formed thereon. Relaxation of the pressure differential allows release of the wafer. The mold sheet may be cooler than the melt. Heat is extracted almost exclusively through the thickness of the forming wafer. The liquid and solid interface is substantially parallel to the mold sheet. The temperature of the solidifying body is substantially uniform across its width, resulting in low stresses and dislocation density and higher crystallographic quality. The mold sheet must allow flow of gas through it. The melt can be introduced to the sheet by: full area contact with the top of a melt; traversing a partial area contact of melt with the mold sheet, whether horizontal or vertical, or in between; and by dipping the mold into a melt. The grain size can be controlled by many means.