High efficiency low cost thin film silicon solar cell design and method for making

Patent · Tue Apr 27 04:00:00 EDT 1999

OSTI ID:350315

Sopori, B. L.

A semiconductor device is described having a substrate, a conductive intermediate layer deposited onto said substrate, wherein the intermediate layer serves as a back electrode, an optical reflector, and an interface for impurity gettering, and a semiconductor layer deposited onto said intermediate layer, wherein the semiconductor layer has a grain size at least as large as the layer thickness, and preferably about ten times the layer thickness. The device is formed by depositing a metal layer on a substrate, depositing a semiconductive material on the metal-coated substrate to produce a composite structure, and then optically processing the composite structure by illuminating it with infrared electromagnetic radiation according to a unique time-energy profile that first produces pits in the backside surface of the semiconductor material, then produces a thin, highly reflective, low resistivity alloy layer over the entire area of the interface between the semiconductor material and the metal layer, and finally produces a grain-enhanced semiconductor layer. The time-energy profile includes increasing the energy to a first energy level to initiate pit formation and create the desired pit size and density, then ramping up to a second energy level in which the entire device is heated to produce an interfacial melt, and finally reducing the energy to a third energy level and holding for a period of time to allow enhancement in the grain size of the semiconductor layer. 9 figs.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-83CH10093
• Assignee: Midwest Research Inst., Kansas City, MO (United States)
• Patent Number(s): US 5,897,331/A/
• Application Number: PAN: 8-745,951
• OSTI ID: 350315
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
DEPOSITION
DESIGN
FABRICATION
GRAIN SIZE
HEAT TREATMENTS
SILICON
SILICON SOLAR CELLS
SUBSTRATES