OPTICAL AND ELECTRICAL-PROPERTIES OF ALUMINUM-OXIDE FILMS DEPOSITED BY SPRAY-PYROLYSIS

The optical and electrical characteristics of spray pyrolysis deposite d aluminum oxide films are reported. The films were deposited from a s praying solution of aluminum acetylacetonate in N,N-dimethylformamide using an ultrasonic mist generator on (100) Si substrates. The additio n of water mist during the spraying deposition process resulted in an overall improvement of the films characteristics. The substrate temper ature during deposition was in 450-650 degrees C range. Deposition rat es up to 90 Angstrom/s were obtained depending on the spraying solutio n concentration and substrate temperature with an activation energy of the order of 31 kJ/mol, The optical energy band gap for these films w as 5.63 eV and the refractive index at 630 nm up to 1.66 was measured by ellipsometry, The electrical characteristics of the films were dete rmined from the capacitance and current versus voltage measurements of metal-oxide-semiconductor (MOS) structures incorporating them. A diel ectric constant of 7.9, interface states density of the order of 10(11 ) X 1/eV cm(2) as well as breakdown fields higher than 5 MV/cm were de termined in this way. (C) 1998 American Institute of Physics. [S0003-6 951(98)03514-1].