Defect formation and strain relaxation in step-graded GaAs1−xNx and GaAs1−yPy buffer structures grown by metal-organic vapor phase epitaxy on GaAs(001) substrates were investigated by transmission electron microscopy and high-resolution X-ray diffractometry. From the comparison of different buffer concepts, it was shown that, by introducing intermediate GaAs1−xNx layers with N concentrations x ≥ 2% into a GaAs1−xPx buffer structure, dislocation formation and strain relaxation were effectively suppressed during subsequent growth of layers with tensile strains. It was argued that a similar concept, however, modified by using layers of differing alloy composition, could be used for layer systems with compressive strains. Appropriately alloyed intermediate dilute nitride layers appear

to offer a powerful concept for engineering defect distributions and layer strain in semiconductor technology.

Misfit Dislocation Blocking by Dilute Nitride Intermediate Layers. J.Schöne, E.Spiecker, F.Dimroth, A.W.Bett, W.Jäger: Applied Physics Letters, 2008, 92[8], 081905