Precursor chemistry of Group III nitrides: Part XVI. Synthesis and structure of monomeric penta-coordinated intramolecularly adduct-stabilized amidobisazides of aluminum, gallium and indium with an all-nitrogen coordination sphere: OMCVD of GaN using (N3)2Ga{N[CH2CH2(NEt2)]2}

Abstract

New intramolecularly Lewis-base-stabilized halogeno alanes, gallanes and indanes of the general formula (X)2M{N[(CH2)n(R′)2]2} (1–6) and (X)2M{N(Et)[(CH2)2N(R′)2]} (7–9) (n=2, 3; R′=Me, Et; X=Cl, Br; E=Al, Ga and In) as well as the azido derivatives (N3)2Ga{N[(CH2)2N(Et)2]} (10) and (N3)2Ga{N(Et)[(CH2)2N(Me)2]} (11) as representative examples of the homologous series were synthesised via standard salt metathesis routes and fully characterised by means of elemental analysis, NMR and IR spectroscopy. Compounds 1, 2, 3 and 10 were studied by X-ray crystallography revealing monomeric structures in the solid state. Compound 10 allowed the growth of crystalline GaN thin films on sapphire substrates at 750°C in the absence of ammonia using the technique of organometallic chemical vapour deposition at reduced pressure. The films were analysed by XRD and Raman spectroscopy showing a preferred orientation of the crystallites perpendicular to the c-plane of the sapphire substrate.