New Test Methods and Chemicals Standards Published
New Test Methods and Chemicals Standards Published
By Kevin Nguyen, SEMI Standards
SEMI published four new photovoltaic standards and the SEMI PV task forces developed two new test methods to measure resistivity and haze, and two chemical specifications providing impurity limits for 2-Propanol and sulfuric acid.
The PV Electrical & Optical Properties Measurement Task Force developed:
- SEMI PV28-0212 Test Methods for Measuring Resistivity or Sheet Resistance with a Single-Sided Noncontact Eddy-Current Gauge
- SEMI PV31-0212 Test Method for Spectrally Resolved Reflective and Transmissive Haze of Transparent Conducting Oxide (TCO) Films for PV Application
Resistivity is an important and a primary quantity for characterization of material used for photovoltaic device. Eddy-current gauges are widely used in the PV area for characterizing resistivity and resistivity related properties of silicon materials. Various standardized test methods are existed. SEMI MF673 is a long and widely used set of test methods for making resistivity and/or sheet resistance measurements on wafers and thin films of silicon. These test methods utilize an instrument with two opposing Eddy-current transducers and the relatively thin wafer or other test specimen is placed between them. An ingot or brick would not fit between the two transducers so only a single transducer is used in these methods. Thin silicon and TCO (transparent conductive oxide) films on non-conducting substrates are also used in the PV industry. Hence, PV28 was written to include both silicon bricks and ingots and thin silicon or TCO films on non-conducting substrates.
In the PV field, haze is taken as the total integrated reflective or transmissive scatter from the surface of a sample. Frequently, haze measurements are used to characterize textured TCO films on glass or amorphous silicon used in the photovoltaic industry to optimize light absorption and maximize cell efficiency. SEMI PV32 provides these test methods for measurement of haze, which be correlated with useful properties.
The Photovoltaic (PV) Gases and Liquid Chemical Purity Standards Task Force completed two new standards.
- SEMI PV30-0212 Specifications for 2-Propanol, Used in Photovoltaic Applications
- SEMI PV33-0212 Specifications for Sulfuric Acid, Used in Photovoltaic Applications
Including the fourteen previously published PV chemical standards, a total of sixteen SEMI chemicals standards for PV manufacturing are now available. The task force is currently working on three additional documents for Potassium Hydroxide, Hydrogen Peroxide, and Flourine. Also, an Auxiliary document is being written to summarize some gas and liquid chemical standards currently published by SEMI so that they can be shared between PV and semiconductor without the need to develop a stand-alone PV application standard.
If you have any questions about participation or would like to join our task force please contact Kevin Nguyen at knguyen@semi.org. For more information on Standards activities at SEMI or upcoming meetings, please visit: www.semi.org/standards or www.pvgroup.org/standards
