Group 13 β-Ketoiminate Compounds: Gallium Hydride Derivatives As Molecular Precursors to Thin Films of Ga2O3

Bis(beta-ketoimine) ligands, [R{N(H)C(Me)CHC(Me)=O}(2)] (L1H2, R = (CH2)(2); L2H2, R = (CH2)(3)), linked by ethylene (L-1) and propylene (L-2) bridges have been used to form aluminum, gallium, and indium chloride complexes [Al(L-1)Cl] (3), [Ga(L-n)Cl] (4, n = 1; 6, n = 2) and [In(L-n)Cl] (5, n = 1; 7, n = 2). Ligand L, has also been used to form a gallium hydride derivative [Ga(L-1)H] (8), but indium analogues could not be made. beta-ketoimine ligands, [Me2N(CH2)(3)N(H)C(R')-CHC(R')=O] (L3H, R' = Me; L4H, R' = Ph), with a donor-functionalized Lewis base have also been synthesized and used to form gallium and indium alkyl complexes, [Ga(L-3)Me-2] (9) and [In(L-3)Me-2] (10), which were isolated as oils. The related gallium hydride complexes, [Ga(L-n)H-2] (11, n = 3; 12, n = 4), were also prepared, but again no indium hydride species could be made. The complexes were characterized mainly by NMR spectroscopy, mass spectrometry, and single crystal X-ray diffraction. The beta-ketoiminate gallium hydride compounds (8 and 11) have been used as single-source precursors for the deposition of Ga2O3 by aerosol-assisted (AA)CVD with toluene as the solvent. The quality of the films varied according to the precursor used, with the complex [Ga(L-1)H] (8) giving by far the best quality films. Although the films were amorphous as deposited, they could be annealed at 1000 degrees C to form crystalline Ga2O3. The films were analyzed by powder XRD, SEM, and EDX.