Columnar-grained polycrystalline solar cell substrate and improved method of manufacture

US6111191A · kind A · utility

Assignee

• ASTROPOWER, INC. · US

Inventors

• Robert B. Hall · Newark, US
• Allen M. Barnett · Landenberg, US
• Sandra R. Collins · Chesapeake City, US
• Joseph C. Checchi · Newark, US
• David H. Ford · Wilmington, US
• Christopher L. Kendall · Wilmington, US
• James A. Rand · New Garden Township, US
• Chad Byron Moore · Corning, US

Key dates

• Filing date: Mar 2, 1998
• Grant date: Aug 29, 2000
• Expiry date: Mar 2, 2018

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/12528

Abstract

The invention relates to improved techniques for manufacturing columnar-grained polycrystalline sheets which have particular utility as substrates or wafers for solar cells. The sheet is made from silicon on a setter material which supports the silicon material. The setter material and silicon are subjected to a thermal profile all of which promote columnar growth. The thermal profile sequentially creates a melt region where a thin-film capping layer grows at the top of the silicon, a nucleation region where preferential nucleation occurs at the capping-layer/molten-silicon interface, and then a growth region where both liquid and a growing polycrystalline sheet layer coexist. An annealing region is created where the temperature of the grown polycrystalline silicon sheet layer is controllably reduced to effect stress relief.