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13 October 2006


NIST releases standard for AlGaAs epilayers

The US National Institute of Standards and Technology (NIST) has issued the first standard for the chemical composition of thin-film semiconductor alloys. Standard Reference Material (SRM) 2841 'Semiconductor Thin Film:
AlxGa1-xAs Epitaxial Layers' (with Al mole fraction x near 0.20) is intended for use as a reference standard to calibrate equipment for making the material or for measuring thin-film composition using analytical methods
such as electron microprobe analysis (EMPA), photoluminescence (PL), auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS).

AlGaAs is used as a barrier material to increase conductivity in high-speed circuits for wireless communication; lasers for optical disk drives, bar code scanning, xerography, and laser surgery; and LEDs for remote controls, traffic lights, and medical instruments. Buyers of SRM 2841 are expected to include companies that grow or characterize thin films or use them to make devices, as well as government and university laboratories.

A unit of SRM 2841 consists of an epitaxial layer of AlxGa1-xAs with a certified Al mole fraction x grown on a GaAs substrate mounted on a stainless-steel disk using adhesive tape. Each unit is sealed in a Mylar envelope containing a nitrogen atmosphere.

The standard is expected to increase the accuracy of chemical characterization of AlGaAs films by an order of magnitude over the current state of the art, says NIST. Improved accuracy should reduce wasteful duplication of reference wafers, increase the free exchange of thin-film
materials between vendors and their customers, and ultimately improve the accuracy of data on relationships between material composition and properties.

SRM 2841 can be ordered at: