Measurement of III-V quaternary composition using X-ray diffraction

A method is demonstrated for the determination of quaternary compositions using a single X-ray measurement. By comparing the integrated intensity of a reflection with theoretical calculations and combining this with the mismatch of the layer, a solution for the composition can be determined. For the quaternary, InAlAsSb, the intensity of the (002) reflection is shown to depend strongly on composition and allow determination of In:Al and As:Sb ratios. Since the bandgap/composition relationship is not well known for this system, the accuracy of the technique is assessed by measuring InAsSb layers using peak intensities and comparing the calculated composition with that determined using the layer mismatch in the usual way. The values calculated by the two techniques are in good agreement and therefore provide confidence in the quaternary compositions measured