AbstractThe single crystalline growth of the GaNxSb1-x system is difficult due to the miscibility gap expected for nearly the whole composition range under thermodynamic equilibrium conditions. The gap is determined by the differences of the atomic radii and of the electro negativities for N and Sb. To overcome this problem crystal growth has to be performed under non-equilibrium conditions with kinetically controlled growth, as it is observed for molecular beam epitaxy (MBE) growth. A single crystalline MBE-growth within the miscibility gap has been demonstrated already in the GaAsxN1-x system exhibiting a similar large miscibility gap. GaN:Sb-layers were grown on Si(111)-substrates by MBE using NH3 as a N-source and solid element sources for Ga and Sb. The parameter window for growth was limited due to side reactions like the decomposition of NH3, the desorption of (at high temperature volatile) compounds like Sb and GaSb or the reaction of Sb with NH3. The composition of the layers was analyzed by XRD and RBS. Antimony bulk concentrations of up to 1.6 % could be obtained in GaN. Optical characterization of the samples was performed by CL-measurements and indicate Sb-induced transitions in the 2.2 eV and 1.42 eV range.