Development of digitally processed DC reactive sputtering and its application to the synthesis of (Er0.1Y0.9)2SiO5layered crystalline thin film

Abstract

We have developed a digitally processed DC reactive sputtering (DPDRS) system that enables synthesis of arbitrarily designed atomically precise deposition of metal oxide compounds. Pulsed-DC sputtering employing a digital pulse pattern generator can perform the temporally alternating process of multiple metal sputtering and oxidation. High-speed switching of the pulsed-DC sputtering process driven by the digital signal processing was confirmed from time-resolved plasma emission spectroscopy. Metal sputtering, which was temporally separated from the oxidation process, resulted in a deposition rate higher than 1 μm/h. It was also found that the temporally separated radical oxidation at the deposited metal surface could control the oxidation process. The DPDRS was applied to layer-by-layer synthesis of (Er0.1Y0.9)2SiO5 (EYSO) films oriented to the 〈100〉direction. The deposition rate for each metal target (Er and Y) was adjusted to 0.86 nm/cycle corresponding to a d-spacing of the (100) plane by changing independently the duty ratio of the base pulse for plasma generation. X-ray diffraction measurements indicated a formation of 〈100〉highly oriented (Er0.1Y0.9)2SiO5 crystalline thin films. Photoluminescence spectra and the decay characteristics also showed synthesis of high crystalline quality EYSO films better than those obtained by pulsed laser deposition.