Depth profiling of strain using micro-Raman measurements

We describe a method to determine the variation of strain with depth in a sample using Raman measurements. The method involves recording Raman spectra using incident light having different absorption coefficients. These can be obtained using a single incident light frequency by adjustment of the point of focus. The Raman spectra are then processed using a Laplace transform to obtain the characteristic elastic strain as a function of depth. The method is illustrated using several model strain distributions. It is applicable to practical. cases such as graded interfaces and strained/relaxed epitaxial layers.