Ryusuke Yamauchi

Combinatorial search for low resistivity Pd-Cu-Si thin film metallic glass compositions

A new combinatorial method to deposit thin films using an arc plasma, Combinatorial arc plasma deposition (CAPD), was applied to search for low resistivity compositions of Pd–Cu–Si thin film metallic glasses (TFMGs). The CAPD setup includes three arc plasma guns (APGs), with each gun shooting a pulse-like plasma of Pd, Cu or Si at specific time intervals to deposit a Pd–Cu–Si thin film on an SiO2 substrate. In this study, a Pd-based compositionally-graded thin film was deposited by controlling the number of shots as well as the plasma strength. The deposited thin film was separated into 1,089 samples (thin film library), and the thickness, composition, phase, and relative resistivity of each sample was evaluated without detaching them from the library. From the samples, three amorphous, low relative resistivity CAPD samples were identified. To verify that these samples were metallic glasses, their compositions were reproduced in samples deposited by sputtering, and their Tg (glass transition temperature) and Tx (crystallization temperature) were measured. The absolute resistivities of the three metallic glass samples were also measured. As the result, the Pd81Cu5Si14 at. % sample showed the lowest absolute resistivity of 64 µ Ω cm and a supercooled liquid region temperature range ( ΔTx=Tx-Tg) of 50 K. This resistivity is 17% lower and the supercooled liquid region is almost two times larger than those of the known Pd-based TFMG composition.

Combinatorial Arc Plasma Deposition of Thin Films

In this paper, we introduce a new combinatorial thin film deposition process that uses arc plasma [combinatorial arc plasma deposition (CAPD)]. The major goal of CAPD in this study is to search for new compositions of amorphous thin film alloys. CAPD uses three cathodic arc plasma guns and the guns shoot the pulse like plasma one by one at a specific time interval. The plasma from each gun is guided onto a substrate by a magnetic field at a specific area on the substrate so as to deposit a compositionally-graded thin film. The deposited thin film is separated into 1,089 samples (the size of each is 1 ×1 mm2) by a trench grid on the substrate. The samples together are called the thin film library and all samples are numbered by the 5-bit row and column marks in the grid. To prove CAPD, a thin film library of a Pd–Cu–Si alloy system was deposited. The composition and non crystallinity of 180 samples were evaluated using energy-dispersive X-ray fluorescence spectrometer (EDX) and imaging-plate X-ray diffractometer (IP-XRD), respectively. Both measurements were performed without detaching the samples from the library. Analysis of 180 samples showed a graded composition, and some of the samples were shown to be amorphous.

Searching for Novel Ru-Based Thin Film Metallic Glass by Combinatorial Arc Plasma Deposition

We found out a novel Ru–Zr–Al thin film metallic glass by combinatorial arc plasma deposition (CAPD). To search for Ru-based thin film metallic glasses, first, a library of 1,089 CAPD samples was deposited, of which fifteen amorphous samples were selected by X-ray diffractometry. The compositions of these samples were measured by energy dispersive X-ray fluorescence spectrometry. From the fifteen samples, two samples having low Al content (Ru65Zr30Al5 and Ru67Zr25Al8, at. %) were chosen, and their compositions were reproduced in samples deposited by sputtering, because the CAPD samples were too small for evaluating the glass transition temperature Tg and crystallization temperature Tx by differential scanning calorimetry (DSC). DSC revealed that the two sputter-deposited samples Ru65Zr30Al5 and Ru67Zr25Al8 had a supercooled liquid region (SCLR), showing a Tg, Tx, and width of SCLR ΔTx (=Tx-Tg) of 902, 973, and 71 K in the case of Ru65Zr30Al5, and 913, 979, and 66 K in the case of Ru67Zr25Al8, respectively. Moreover, the sputter-deposited samples Ru65Zr30Al5 and Ru67Zr25Al8 exhibited superior mechanical properties. The fracture stress σf, elastic limit el, and Youngs modulus E were 1.9 GPa, 2.0% and 92.7 GPa, respectively, for Ru65Zr30Al5 and 1.9 GPa, 2.0%, and 91.6 GPa, respectively, for Ru67Zr25Al8.