Midwest Research Institute

Alliance for Sustainable Energy, LLC

Tihu Wang

Theodore F Ciszek

Qi Wang

Matthew Robert Page

Yanfa Yan

Eugene Iwaniczko

Theodore J Ciszek

A system and a process for forming a semi-conductor device, and solar cells () formed thereby. The process includes preparing a substrate () for deposition of a junction layer (); forming the junction layer () on the substrate () using hot wire chemical vapor deposition; and, finishing the semi-conductor device.

Low temperature junction growth using hot-wire chemical vapor deposition

In a method of making a c-Si-based cell or a &#x3bc;c-Si-based cell, the improvement of increasing the minority charge carrier's lifetime, comprising: a) placing a c-Si or polysilicon wafer into CVD reaction chamber under a low vacuum condition and subjecting the substrate of the wafer to heating; and b) passing mixing gases comprising NH/Hthrough the reaction chamber at a low vacuum pressure for a sufficient time and at a sufficient flow rate to enable growth of an a-Si:H layer sufficient to increase the lifetime of the c-Si or polysilicon cell beyond that of the growth of an a-Si:H layer without treatment of the wafer with NH/H.

Method for passivating crystal silicon surfaces

In a single crystal pulling apparatus for providing a Czochralski crystal growth process, the improvement of a shallow melt crucible () to eliminate the necessity supplying a large quantity of feed stock materials that had to be preloaded in a deep crucible to grow a large ingot, comprising a gas tight container a crucible with a deepened periphery () to prevent snapping of a shallow melt and reduce turbulent melt convection; source supply means for adding source material to the semiconductor melt; a double barrier () to minimize heat transfer between the deepened periphery () and the shallow melt in the growth compartment; offset holes () in the double barrier () to increase melt travel length between the deepened periphery () and the shallow growth compartment; and the interface heater/heat sink () to control the interface shape and crystal growth rate.

Shallow melt apparatus for semicontinuous czochralski crystal growth

Method and apparatus for producing purified bulk silicon from highly impure metallurgical-grade silicon source material at atmospheric pressure. Method involves: (1) initially reacting iodine and metallurgical-grade silicon to create silicon tetraiodide and impurity iodide byproducts in a cold-wall reactor chamber; (2) isolating silicon tetraiodide from the impurity iodide byproducts and purifying it by distillation in a distillation chamber; and (3) transferring the purified silicon tetraiodide back to the cold-wall reactor chamber, reacting it with additional iodine and metallurgical-grade silicon to produce silicon diiodide and depositing the silicon diiodide onto a substrate within the cold-wall reactor chamber. The two chambers are at atmospheric pressure and the system is open to allow the introduction of additional source material and to remove and replace finished substrates.

Purified silicon production system

Purification and deposition of silicon by an iodide disproportionation reaction

A process for depositing polycrystalline silicon on substrates, including foreign substrates, occurs in a chamber at about atmospheric pressure, wherein a temperature gradient is formed, and both the atmospheric pressure and the temperature gradient are maintained throughout the process. Formation of a vapor barrier within the chamber that precludes exit of the constituent chemicals, which include silicon, iodine, silicon diiodide, and silicon tetraiodide. The deposition occurs beneath the vapor barrier. One embodiment of the process also includes the use of a blanketing gas that precludes the entrance of oxygen or other impurities. The process is capable of repetition without the need to reset the deposition zone conditions.

Process for Polycrystalline film silicon growth

A liquid phase epitaxy method for forming thin crystalline layers of device quality silicon having less than 3.times.10.sup.16 Cu atoms/cc impurity, comprising: preparing a saturated liquid solution of Si in a Cu/Al solvent at about 20 to about 40 at. % Si at a temperature range of about 850.degree. to about 1100.degree. C. in an inert gas; immersing or partially immersing a substrate in the saturated liquid solution; super saturating the solution by lowering the temperature of the saturated solution; holding the substrate in the saturated solution for a period of time sufficient to cause Si to precipitate out of solution and form a crystalline layer of Si on the substrate; and withdrawing the substrate from the solution.

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Littleton, CO, United States of America

Tihu Wang