Chemical vapor deposition of GaP and GaAs thin films from [ ⁿBu₂Ga(μ- e ^tBu₂) ₂GaⁿBu₂] (E = P or As) and Ga(P ^tBu₂)₃

Low pressure chemical vapor deposition (LPCVD) using the single-source precursors [ⁿBu₂Ga(μ-E^tBu₂) ₂GaⁿBu₂] (E = P or As) in the temperature range 723-823 K (0.05 mmHg), gives shiny yellow or silvery gray films of GaP and GaAs, respectively, on silica. The composition and morphology of the deposited materials have been probed via X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray (SEM/EDX), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and Raman spectroscopy, revealing crystalline (cubic) GaE with 1:1 Ga/E ratios. The GaP forms nanorods growing perpendicular to the substrate surface and is rougher than the GaAs, which appears to form smaller, densely packed microcrystallites. While the GaAs films produced in this way did not exhibit any significant luminescence, the reflective GaP films obtained by LPCVD were of good electronic quality, revealing photoluminescence comparable to that of a single crystalline GaP reference. LPCVD using Ga(P^tBu₂)₃ gives GaP, although this appears to be an inferior reagent compared to the dimer. Unlike the corresponding [ⁿBu₂In(μ-E^tBu ₂)₂InⁿBu₂] dimers (see Aksomaityte et al., Chem. Mater.2010, 22, 4246) which gave InE films and nanowires from supercritical chemical fluid deposition in sc-CO₂/hexane, under the same conditions (773 K, 12 MPa), the gallium dimer precursors mostly failed to give GaE. Instead significant carbon deposition occurred, indicating solvent degradation.