Layer thickness and variation of layer thickness of III-V semiconductor thin layer structures, such as in GaAs--AlGaAs superlattices, play a vital part in determining the properties of electronic and optical devices. For example, layer thickness determines the threshold voltages in heterojunction field effect transistors and the energy levels in quantum well infrared detectors. Heretofore, layer thicknesses in superlattice structures have been measured through methods such as, secondary ion mass spectroscopy (SIMS), Auger electron spectroscopy (AES), shallow angle lapping and/or transmission electron microscopy (TEM). Unfortunately, these methods have their limitations. For example, depth resolution derived by SIMS and AES analysis is limited to a few nanometers due to ion beam mixing. Further, mechanical shallow angle lapping is time consuming process involving several polishing and cleaning steps, as well as chemical etching. Furthermore, mechanical angle lapping can resolve layers in the 8-10 nm range and only provide information about the layer thickness at the beveled edge. So far, TEM has proven the most accurate method for measuring the thickness of superlattice layers, however, preparation of TEM cross-sectional samples is very time consuming and tedious, requiring mechanical grinding, polishing, and ion milling. Further, TEM requires a substantial amount of material and it provides thickness information about only one point on the wafer. Therefore, a need exists to provide for a cost effective, simple way to determine the thicknesses of layers in heterostructures.