Influence of composition and processing parameters on the properties of solution-processed aluminum phosphate oxide (AlPO) thin films

Abstract The effects of precursor solution concentration, composition, and spin-processing parameters on the thickness and electrical properties of ultra-smooth aluminum oxide phosphate (Al 2 O 3−3x (PO 4 ) 2x or “AlPO”) thin films prepared using aqueous solutions are reported. Compositions were verified by electron probe micro-analysis and range from Al 2 O 1.5 (PO 4 ) to AlPO 4 (x = P:Al from 0.5 to 1.0). Film thicknesses were determined using X-ray reflectivity measurements and were found to depend systematically on solution concentration, P:Al ratio, and spin-speed. Metal-insulator-semiconductor devices were fabricated to determine electrical properties as a function of composition. As the P:Al ratio increased from 0.5 to 1.0, the dielectric constant decreased from 6.0 to 4.6, leakage currents increased from 0.45 to 65 nA cm −2 at 1 MV cm −1 and dielectric breakdown (defined as leakage currents >10 μA cm −2 ) decreased from 9.74 to 2.84 MV cm −1 . These results establish composition, concentration, and spin-speed for the production of AlPO films with targeted thicknesses and electrical properties.