Evaluating epitaxial growth stability

We have investigated variations of epitaxial layer thicknesses from uniform periodicity in compound semiconductor Bragg-reflectors experimentally and theoretically. Specifically, we characterized the variation of individual layer thicknesses in the growth direction at a given point on the wafer, thereby assessing the growth stability in time. The characterization is based on the correlation of experimental reflectance spectroscopy and high resolution X-ray diffractometry measurements and precisely fitted simulations made on growth runs which include both random and systematic variations from perfect periodicity. We find good agreement between the measurement techniques and between the measurements and their simulations.