Characterization of InGaN/GaN and AlGaN/GaN superlattices by X‐ray diffraction and X‐ray reflectivity measurements

The commercial significance of superlattice structures is increasing due to greater demand of optoelectronic devices, such as the light emitting diode (LED). In order to optimize these devices, an accurate and reliable characterization method is needed. This paper describes in detail the characterization of superlattices with X-ray scattering techniques. The thicknesses of the individual layers are determined by X-ray reflectivity (XRR) measurements and the state of strain, the lattice constants and the compositions of ternary compounds by X-ray diffraction (XRD) measurements. The method is non-destructive, and yields unique results, unlike characterizations based on simulation of symmetric XRD scans. These simulations were used for verification of results. The method was tested on InGaN and AlGaN superlattice structures. The measured and simulated parameter values agreed very well. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)