SEMI PV15 - Guide for Defining Conditions for Angle Resolved Light Scatter Measurements to Monitor the Surface Roughness and Texture of PV Materials
This Standard was technically approved by the Photovoltaic - Materials Global Technical Committee. This edition was approved for publication by the global Audits and Reviews Subcommittee on December 4, 2015. Available at www.semiviews.org and www.semi.org in December 2015; originally published February 2011.
NOTICE: This Document was reapproved with minor editorial changes.
Many surfaces used in the photovoltaic industry are textured in order to optimize light absorption and maximize cell efficiency. The required texture usually is not well defined by a single roughness, gloss, or haze specification because the relative amounts of low and high frequency roughness on the surface can both be important.
Light scatter measured over a range of collection angles (or several individual angles) provides a fast, economical means to monitor, but not to quantify, texture over a range of roughness frequencies. Such measurements allow several degrees of freedom, such as incidence angle, scatter angle, light wavelength, aperture, spot size, etc., which need to be agreed upon between involved parties in order to be able to obtain comparable measurement results. Therefore means are required to uniquely define the measurement parameters, and to allow them to be easily exchanged.
This Guide covers the language necessary to define scatter measurement conditions to enable measurements that describe changes in the scatter pattern that are present with differences in surface texture. It is not intended to distinguish good from bad or desirable from undesirable, to set scatter levels, or to determine the measurements to be taken.
This Guide covers angle resolved light scatter (ARLS) measurements performed on monocrystalline (also known as single crystal) and multicrystalline (also known in some regions as polycrystalline) semiconductor wafer surfaces, transparent substrate surfaces, and coated transparent surfaces that may have been purposely modified (textured) to achieve desired reflective and/or transmissive properties.
Referenced SEMI Standards
SEMI M59 — Terminology for Silicon Technology
SEMI ME1392 — Guide for Angle Resolved Optical Scatter Measurement on Specular or Diffuse Surfaces
SEMI MF1048 — Test Method for Measuring Reflective Total Integrated Scatter
SEMI MF1811 — Guide for Estimating the Power Spectral Density Function and Related Finish Parameters from Surface Profile Data