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