A study of bisazido(dimethylaminopropyl)gallium as a precursor for the OMVPE of gallium nitride thin films in a cold-wall reactor system under reduced pressure

The use of alternative nitrogen sources for growing GaN materials by organo metallic vapor phase epitaxy (OMVPE) is being continuously investigated in the hope of achieving device-quality films under moderate conditions, in co mparison to conventional methods. Employing the single molecule precursor ( N-3)(2)Ga[(CH2)(3)NMe2], and using a cold-wall CVD reactor, epitax ial film s of GaN, transparent in appearance and stoichiometric in composition, were deposited on c-plane sapphire, in the absence of ammonia, above 1073 K, un der low pressures (between 0.080 and 100.0 mbar). Dense, amorphous, and ver y smooth films were grown at temperatures as low as 773 K. The influence of substrate temperature, reactor pressure, and the effect of small quantitie s of additional ammonia, on the growth rate and the film properties, were s tudied in some detail. The films were characterized by high-resolution X-ra y diffraction (XRD) (e.g., full width at half maximum (FWHM) of the 0002 Ga N rocking curve of 130 arcsec), X-ray reflectometry, scanning electron micr oscopy (SEM), atomic force microscopy (AFM) (root mean square roughness of 1.9 nm), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscop y (AES), Rutherford backscattering (RBS) (Ga/N = 1:1 +/- 0.05), and photolu minescence (PL) measurements (band edge luminescence at 3.45 eV and FWHM of 0.22 eV at 300 K).