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System for characterizing semiconductor materials and photovoltaic devices through calibration

United States Patent

5,757,474
May 26, 1998
View the Complete Patent at the US Patent & Trademark Office
National Renewable Energy Laboratory - Visit the NREL Technology Transfer Website
A method and apparatus for measuring characteristics of a piece of material, typically semiconductor materials including photovoltaic devices. The characteristics may include dislocation defect density, grain boundaries, reflectance, external LBIC, internal LBIC, and minority carrier diffusion length. The apparatus includes a light source, an integrating sphere, and a detector communicating with a computer. The measurement or calculation of the characteristics is calibrated to provide accurate, absolute values. The calibration is performed by substituting a standard sample for the piece of material, the sample having a known quantity of one or more of the relevant characteristics. The quantity measured by the system of the relevant characteristic is compared to the known quantity and a calibration constant is created thereby.
Sopori; Bhushan L. (Denver, CO), Allen; Larry C. (Arvada, CO), Marshall; Craig (Littleton, CO), Murphy; Robert C. (Golden, CO), Marshall; Todd (Littleton, CO)
Midwest Research Institute (Kansas City, MO)
08/ 496,061
June 28, 1995
CONTRACTUAL ORIGIN OF THE INVENTION The United States Government has rights in this invention under Contract No. DE-AC36-83CH10093 between the U.S. Department of Energy and the National Renewable Energy Laboratory, a Division of Midwest Research Institute.