Quantitative imaging of residual strain profile in large diameter GaAs substrates

A near-infrared imaging polariscope (NIRIP) has been developed quantitatively to measure residual strain profiles in large-diameter GaAs substrates, in which a near-infrared camera connected to an image-processing system is used as a 2D multi-channel sensor and also a collimated light beam is used to illuminate the whole area of substrate, in addition to a pair of computer-controlled rotating polarizer and analyser. The measurement time is less than 5 minutes for the GaAs substrate with the diameter of 6-inch, which is drastically reduced in comparison to that of the scanning infrared polariscope (SIRP) using a single channel sensor and a focused light beam. By comparing the residual strain profiles measured in the same substrates with NIRIP and SIRP, it is confirmed that the NIRIP developed here has the sensitivity equivalent to the SIRP. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)