A STUDY OF ION-BEAM MODIFICATION OF COMNNIO AMORPHOUS FILMS

Abstract CoMnNiO amorphous film is a thermally sensitive material with negative temperature coefficient. In this study, CoMnNiO film samples are deposited on an oxidized Si substrate by means of rf sputtering. The samples are then implanted with 360 keV, 1 × 10 16 cm −2 Cu + and 100 keV, 1 × 10 16 cm −2 Mg + ions, respectively, and thermally annealed at 500–900°C for 4 h in O 2 atmosphere. The experimental results indicate that the resistivity of Cu + and Mg + implanted samples annealed at temperatures below 550°C is lower than that of unimplanted samples. When annealed above 600°C, the resistivity of Cu + implanted films decreases with increasing annealing temperature due to the formation of a Cu cubic spinel solid solution having relatively good conductivity. When annealed above 900°C, part of the cubic spinel is resolved and low-valence oxides such as CuO, CoO, and NiO are produced, while the resistivity of the film samples is increased. When Mg + implanted film is annealed above 600°C, its resistivity increases, but when annealed above 900°C, its resistivity decreases obviously, in the same way as conventional thermally sensitive material including Mg. It is also shown that Cu + and Mg + implantation of the CoMnNiO films can improve the electrical properties and the linearity of resistance-temperature characteristics of the films. Using ion beam modification, an applicable temperature sensitive material having a wide operating range can be obtained.