Preparation and properties of AlN (aluminum nitride) powder/thin films by single source precursor

Abstract

The aluminum nitride (AlN) powder/thin films were prepared from an aluminum–urea complex. The complex, hexa urea aluminate(III) chloride, has proven to be a potential single source precursor to aluminum nitrides because urea molecules construct a coordination sphere around the metal atom and form a stable structure, compared with air sensitive halide and hydride precursors. The precursor and the spin coated thin films of the precursor on quartz and Si(100) substrates were pyrolysed at various temperatures (800 °C to 1000 °C) and pressure (100 Torr to 1 Torr) under nitrogen atmosphere. The pyrolysed powders/films were characterized by FTIR (Fourier Transform Infrared) spectroscopy, TGA (Thermogravimetric analysis), PXRD (Powder X-ray Diffraction), FESEM (Field emission scanning electron microscopy), UV-Vis (Ultra violet-Visible spectroscopy), etc. The XRD results show that the polycrystalline aluminum nitride was obtained at a temperature of 1000 °C and at 1 Torr pressure. The average crystallites size calculated from XRD were in the range of 20–10 nm, which decreased with increase of pyrolysis temperature. We also conducted the pyrolysis process under argon instead of nitrogen and found that most of the nitrogen came from urea for the formation of AlN but the nitrogen atmosphere favoured clean formation of AlN. The band gaps of the deposited films were found in the range of 5.1–6.2 eV.