nMolecular Precursors to Group 13 Nitrides,14 Synthesis and Structures of (N_3)_2Ca[(CH_2)_3NMe-2],(N_3)Ga[(CH_2)_3NMe_2]_2 and (N_3)_3Ga(NR_3)(R=CH_3,C_2H_5)

摘要

The synhtesis, properties and X-ray single crystal structure analysis of the intramolecularly adduct-stabilised organogallium bisazide (N_3)_2Ca[(CH_2)_3NMe-2](1),the mono azide(N_3)_2Ca[(CH_2)_3NMe-2]_2 (2) and the trialkylamine adducts of triazidogallium of the type(N_3)_2Ca(NR_3)(3a-d;R=alkyl)are reported. An unusual isomer 1b of compound 1 is described, which was obtained by slow cooling of the analytically pure neat liquid compound 1 to 0deg C. The new and unusual structure 1b can be regarded as a weak associate of dimers linked together by head-to-tail azide bridges. In contrast, compounds 2 and 3-b (R=CH_3,C_2H_5) are monomeric in the solid state. The suitability of the volatile compounds 1 and 2 as single source precursors to grow GaN thin films by chemical vapour deposition is compared, showing that preferentially oriented crystalline films can be obtained from compound 2 on sapphire substrates at 600-700deg C in vacuo (0.1 Pa),However the films have a grey rather than a transparent appearance, which is presumably due to N-deficiency owing to the lower N-content of the single molecule precursor 2 relative to 1.