A STUDY OF THE ELECTRICAL PROPERTIES OF Al2O3 FILMS DEPOSITED ON GaAs SUBSTRATES BY SPRAY PYROLYSIS
Electrical characteristics of high quality aluminum oxide thin films deposited by the spray pyrolysis technique on GaAs substrates are reported. The films were deposited using a spraying solution of aluminum acetylacetonate in N,N-dimethylformamide and an ultrasonic mist generator. The substrates were (100) GaAs wafers Si-doped (1018 cm -3). The substrate temperature during deposition was in the range of 300–600°C. The electrical characteristics of these films were determined by capacitance and current versus voltage measurements by the incorporation of these films into metal-oxide-semiconductor structures. The interface state density resulted in the order of 1012 1/ eV-cm 2 and the films can stand electric fields higher than 5 MV/cm, without observing a destructive dielectric breakdown. The refractive index, measured by ellipsometry at 633 nm, resulted close to 1.64. The determination of the chemical composition of the films was achieved by energy dispersive X-ray spectroscopy; it resulted close to that of stoichiometric aluminum oxide (O/Al = 1.5) when films are deposited at substrate temperatures of 300–350°C.