Syntheses, X-ray structures and CVD studies of diorganoalkoxogallanes

Structural studies by X-ray crystallography have been carried out for a range of diorganoalkoxogallanes incorporating donor-functionalized ligands. The compounds [Et2Ga(μ-OR)]2 (1, R = CH2CH2NMe2; 2, R = CH(CH3)CH2NMe2; 3, C(CH3)2CH2OMe; 4, R = CH(CH2NMe2)2) adopt dimeric structures with a planar Ga2O2 ring, and each gallium atom is coordinated in a distorted trigonal bipyramidal geometry. Low pressure chemical vapor deposition (CVD) of 2 and 4 resulted in the formation of oxygen deficient gallium oxide thin films on glass. However, the reaction of Et3Ga and ROH (R = CH2CH2NMe2, CH(CH3)CH2NMe2, C(CH3)2CH2OMe, CH(CH2NMe2)2) in toluene under aerosol assisted (AA)CVD conditions afforded stoichiometric Ga2O3 thin films on glass. This CVD technique offers a rapid, convenient route to Ga2O3, which involves the in situ formation of diethylalkoxogallanes, of the type [Et2Ga(μ-OR)]2, the structures of which are described in this paper. The gallium oxide films were deposited at 450 °C and analyzed by scanning electron microscopy (SEM), X-ray powder diffraction, wavelength dispersive analysis of X-rays (WDX), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy.