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

Abstract

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 | ε r− ε t| measured by SIRP throughout the wafer thickness was about 10 −5, while it derived from the single components ε xx, ε yy , and ε 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.