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Contamination‐free TiNx was prepared and the lattice parameter (a0)–nitrogen content (x) relation determined. The result can be expressed as a0 = 4.1925 + 0.0467x (in Å) in the range 0.605 ≤x≤ 0.999. Density measurement showed that no titanium vacancies existed in the lattice.

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Fluctuation-free electron emission is obtained from MIM (Al-Al2O3-Au) cathodes. The Al2O3 layer is fabricated by anodic oxidation with a reduced electrolysis current density, i.e., a reduced oxidation rate. The slow oxidation process improves the insulating effect of the Al2O3 layer, and enables the MIM cathodes to operate in the non-formed state. The fluctuation-free emission is reproducible when the diode voltage is cut off instantaneously. With a thin Al2O3 layer, the diode voltage reguired for the cathode operation is reduced to values slightly above the work function of the top electrode.

We propose a novel fabrication technique based on the formation of a Nb protective layer on a MgB2 thin film and high-temperature post-annealing to increase the critical current density (J c) of MgB2 films under an external magnetic field. Analyses of the crystal structure and the composition of the processed MgB2 films confirmed the suppression of the evaporation and oxidation of Mg by high-temperature annealing above 550 °C. The MgB2 film annealed at 650 °C exhibited a J c of 1.62 MA cm−2 under 5 T, which is the highest reported value for MgB2 films, wires, and bulk samples to date.

We are now developing a new in situ deposition process for MgB 2 film as a candidate method to massproduce MgB 2 thin film superconducting tape. In the new method, a MgB 2 film is deposited on a heated metal substrate by a hybrid deposition method, which consists of thermal evaporation of magnesium and sputtering of boron. By using the hybrid deposition method, the substrate temperature can raise from 250 to 350°C, while its fluctuation is kept less than 1°C, which will improve the quality and reproducibility of MgB 2 film in mass production. The J c of MgB 2 film deposited by the hybrid deposition method at 20 K and self-field was more than 30,000 A mm −2 , which was better than the results reported by the two-step in situ process using DC sputtering and 830°C high-temperature post annealing [1] or by the as-grown depostion using sputttering targets of Mg and B [2]. Although we obtained better J c than other deposition methods that use sputtering process, the J c is still lower than the value we obtained by using a co-evaporation method with electron beam (EB). We investigated the film structure and J c -B-T properties of the film made by the hybrid deposition method and compared them with those of the film made by co-evaporation. From the analysis results, we think the reasons for the lower J c are the larger amount of heterogeneous phases such as magnesium oxides in the film and the amorphous B phase under the MgB 2 . We expect to improve the the crystal qualities and superconductivities of the MgB 2 film deposited by the new method by removing impurities in Ar gas during sputtering and thinning the B amorphous phase by increasing the Mg deposition rate in the initial stage of deposition.

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