Infrared and electrical characterization of multilayered n-type GaAs wafers

Abstract
We have characterized GaAs epitaxial wafers (N active/N+ buffer/N+ substrate) intended for varactors and mixer diodes. IV and CV measurements demonstrated that the active layers were excellent. Transmission‐loss measurements suggested that the buffer‐layer carrier concentrations were too low and/or the wafers had an additional high‐resistivity interface layer. The layer thicknesses were measured using a spherical drilling technique followed by chemical delineation. Analysis of infrared reflectance measurements provided the carrier concentrations of the layers as well as their thicknesses. Both the drilling‐delineation measurements and the reflectance measurements confirmed the transmission‐loss indications.