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A New Slant on Semiconductor Characterization

A density color map of a two-inch wafer, calibrated by dicing into samples and measuring the local density of various samples.

A new mathematical method has made semiconductor characterization more efficient, more precise, and simpler.

Credit: Northwestern University Newscenter

Northwestern University researchers say they have developed a mathematical method that makes semiconductor characterization more efficient, more precise, and simpler.

The method involves flipping the magnetic field and repeating one measurement, enabling researchers to quantify whether or not electrical conductivity is uniform across the entire material, a quality required for high-performance semiconductors.

"We have figured out how to measure a single piece of material in a magnetic field while flipping the polarity to deduce the average variation in the density of electrons across the sample," says Northwestern professor Matthew Grayson.

The researchers found the contacts at the edge of the sample reveal information about variations occurring throughout the body of the sample. By adding impurities to a semiconductor material, researchers can modulate the semiconductor's electrical properties. However, they have to ensure the material is uniformly modulated so every part of the material performs equally well.

The technique enables researchers and manufacturers to directly quantify such non-uniformities, and it can be applied to samples as large as a 12-inch wafer or as small as an exfoliated 10-micron flake.

The researchers note the method is especially useful for two-dimensional materials such as graphene, which are too small for researchers to make several measurements across the surface.

From Northwestern University Newscenter
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Abstracts Copyright © 2015 Information Inc., Bethesda, Maryland, USA


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