Methods for determining elastic strains from electron backscatter diffraction and electron channelling patterns

Two approaches to the measurement of elastic strains from electron channelling patterns (ECPs) and electron backscatter diffraction (EBSD) patterns are assessed. Analysis of the shift in channelling (or Kikuchi) line positions has been shown to yield strain sensitivities of up to 3 parts in 104 when {10 10 O} lines in ECPs are used. The lack of such fine detail in EBSD patterns restricts such methods to strains at least one order of magnitude greater. For EBSD an alternative method is presented in whichelastic strains are determined from measurements of small shifts in zone axis positions. The strain sensitivity of the method was found to be 2 parts in 10⁴. Measurements, using this method, of elastic strains in Si_1-xGe_x epitaxial layers grown on Si substrates gave excellent agreement with X-ray diffraction data. The EBSD technique is capable of determining elastic strain variations at submicrometre resolution.