Synthesis of cubic aluminum nitride by VLS technique using gold chloride as a catalyst and its optical and field emission properties

Thin films of nanocrystalline cubic AlN were synthesized by vapor-liquid-solid (VLS) route on Si and fused silica substrates at appropriate conditions. The formation of cubic AlN was confirmed by X-ray diffraction studies. We also observed that AuCl3 plays an important role as a catalyst in the synthesis of well crystalline cubic phase of AlN. Energy dispersive analysis of X-rays confirmed the presence of nearly stoichiometric aluminum and nitrogen in the films. Optical properties of the cubic AlN films deposited on the fused silica substrates were studied by measuring the transmittance versus wavelength. The films showed good transparency and the allowed indirect band gap, measured from the transmittance spectra, was 3.83 eV. Fourier transformed infrared spectra showed characteristics absorptions of different vibrational frequencies. The cubic AlN nanostructured films also showed good electron field emission properties. The turn on field was found to be 11.9 V/μm and the maximum current density was ∼1 A/m2.