EVALUATING EPITAXIAL-GROWTH STABILITY

We have investigated variations of epitaxial layer thicknesses from un iform periodicity in compound semiconductor Bragg-reflectors experimen tally and theoretically. Specifically, we characterized the variation of individual layer thicknesses in the growth direction at a given poi nt on the wafer, thereby assessing the growth stability in time. The c haracterization is based on the correlation of experimental reflectanc e spectroscopy and high resolution X-ray diffractometry measurements a nd precisely fitted simulations made on growth runs which include both random and systematic variations from perfect periodicity. We find go od agreement between the measurement techniques and between the measur ements and their simulations. (C) 1997 Elsevier Science S.A.