Residual strain in annealed GaAs single-crystal wafers as determined by scanning infrared polariscopy, X-ray diffraction and topography

We have compared the strain data in GaAs wafers, as-grown as well as annealed, determined by means of the scanning infrared polariscope (SIRP) with data of high-resolution X-ray diffraction (HRXD) and qualitative results of a synchrotron based, single-crystal X-ray transmission topography (SXRTT) study. The in-plane strain component \epsilon(r) - epsilon(t)\ measured by SIRP throughout the wafer thickness was about 10(-5), while it derived from the single components epsilon(xx), epsilon(yy), and epsilon(xy) determined by HRXD at a penetrated layer close to the surface was above 10(-4). Consequently, we assume that a strong strain gradient exists between the surface and the bulk. (C) 2000 Published by Elsevier Science B.V. All rights reserved.