Combined use of ion backscattering and x-ray rocking curves in the analyses of superlattices

Abstract

Detailed compositional and structural analyses of superlattices have been carried out by mega-electron-volt ${\mathrm{He}}^{+}$ backscattering with channeling and with x-ray rocking curves. Through the combined use of the two techniques, depth profiles of strain, composition, and crystalline quality have been determined. An example of an ${\mathrm{Al}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As/GaAs strained-layer-superlattice (SLS) is considered. The thicknesses of the individual periods in these SLS structures were accurately measured by backscattering spectrometry. The values so obtained were used in the detailed calculations of x-ray rocking curves. Excellent agreement between measured and calculated curves was achieved. Transition regions at the interfaces of the various layers in the SLS were also detected and measured by both techniques. The two techniques complement each other and together provide powerful quantitative tools to characterize SLS structures.