Bulletin of the American Physical Society
75th Annual Gaseous Electronics Conference
Volume 67, Number 9
Monday–Friday, October 3–7, 2022;
Sendai International Center, Sendai, Japan
The session times in this program are intended for Japan Standard Time zone in Tokyo, Japan (GMT+9)
Session GF3: Plasma Deposition |
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Chair: Masaru Hori, Nagoya University Room: Sendai International Center Shirakashi 2 |
Friday, October 7, 2022 1:30PM - 2:00PM |
GF3.00001: Deposition of silicon-based thin films with atmospheric-pressure plasmas Invited Speaker: Matteo Gherardi Plasma enhanced chemical vapor deposition (PECVD) is a unique technique to produce coatings with characteristics suitable for a wide range of applications, including electronics, aerospace, and medicine. Despite the technology is well-established at low pressure (LP), atmospheric pressure (AP) PECVD is receiving a lot of attention due to the absence of expensive vacuum equipment and the possibility of industrial on-line processing. Organosilicon compounds, such as tetraethyl orthosilicate (TEOS) and hexamethyldisiloxane (HMDSO), are excellent precursors for atmospheric pressure plasma polymerization since the chemical-physical characteristics of the deposited thin films can be tailored by properly controlling process parameters. Despite the large body of works on the subject available in the scientific literature, there is still a limited understanding of the fundamental mechanisms of atmospheric pressure plasma polymerization of organosilicon precursor. |
Friday, October 7, 2022 2:00PM - 2:15PM |
GF3.00002: Process analysis of cracking a-C:H/CNP/a-C:H sandwich films under stress using nanoindentation Shinjiro Ono, Takamasa Okumura, Kunihiro Kamataki, Naoto Yamashita, Naho Itagaki, Kazunori Koga, Masaharu Shiratani Stress reduction has been a topic of great interest for applications of hydrogenated amorphous carbon (a-C:H), which play an important material for protective coating. However, increasing mass density and thickness of films resulted in cracking the films due to their stress. So far, we have succeeded in reducing the film stress by fabricating a sandwich structure of a-C:H/carbon nanoparticle(CNP)/a-C:H [1]. The stress for 8.9 % in the CNP coverage decreased 35.8 % of that for the films without CNP insertion. Here, we studied the cracking process of the films by performing nanoindentation on sandwiched a-C:H films to elucidate the mechanism of the stress reduction by CNP insertion. We performed nanoindentation to apply the external stress to our sandwiched films. We found that a displacement jump occurs at a minimum of 5 mN for coverage of 4.4 % and 10 mN for coverage of 8.9 %. The displacement at the displacement jump was approximately equal to the thickness of the second layer of the a-C:H film. These results suggested that the adhesion of the film is increased by the CNPs layer, and cracking occurs at the interface between two the a-C:H layers. |
Friday, October 7, 2022 2:15PM - 2:30PM |
GF3.00003: Deposition of zinc oxide film using high power impulse magnetron sputtering Katsunori Nagahashi, Takayuki Ohta Zinc oxide (ZnO) is a semiconductor material with a hexagonal crystal structure and a wide band gap of 3.37 eV and is expected for various applications such as channel layer in thin film transistors (TFTs), transparent conductive film, and so on. It is reported that c-axis oriented crystalline ZnO achieved high mobility. High power impulse magnetron sputtering (HiPIMS) can produce many energetic ions due to high plasma density and enhance the ion bombardment. In this study, the oxygen gas flow ratio dependence on the deposition of crystalline ZnO by HiPIMS was investigated. |
Friday, October 7, 2022 2:30PM - 2:45PM |
GF3.00004: Sputter epitaxy of Mg-doped ZnO films on sapphire substrates using inverted Stranski-Krastanov mode Masaharu Shiratani, Daichi Takahashi, Naoto Yamashita, Naho Itagaki Mg-doped ZnO has a theoretically wide band gap scope from 3.37 eV to 7.8 eV. Its slight lattice mismatch is attributed to the large band gap (7.8 eV) of MgO and the close proximity of ionic radii between Mg2+ (0.57 Å) and Zn2+ (0.60 Å). Here, we have succeeded in inverted SK growth of Mg-doped ZnO films on 18% lattice mismatched sapphire substrates 1), where buffer layers consisting of 3D islands initially form and relaxed 2D layers subsequently grow on the buffe layers 2). We have realized band gap tuning of Mg-doped ZnO films in the range 3.5–4.3 eV controlling Mg concentration and observed sharp peaks due to exciton absorption in photo-absorption spectra even at room temperature. These results open a new avenue to make high-performance optoelectronic devices that consist of heterostructures. |
Friday, October 7, 2022 2:45PM - 3:00PM |
GF3.00005: Deposition of Rutile TiO2 Thin Films Using high power pulsed magnetron sputtering Miyuki Nishimura, Takayuki Ohta Rutile TiO2 can be used for optical glass and capacitor due to feature of high refractive index and high permittivity, respectively. Generally, substrate heating or annealing after the deposition is required to obtain rutile TiO2. In the present study, high power pulsed magnetron sputtering (HPPMS) was used for depositing rutile TiO2 without substrate heating. HPPMS allows to generate high density plasma resulting in providing kinetic energy by ions bombardment. |
Friday, October 7, 2022 3:00PM - 3:30PM |
GF3.00006: Next-generation Li-ion battery achieved by the low temperature plasma processes Invited Speaker: Giichiro Uchida The automobile industry is currently shifting towards hybrid and electric vehicles powered by electrochemical energy storage systems, or batteries. However, these batteries are less fuel efficient than conventional gasoline systems, and it is therefore important to develop high-performance batteries that have a high energy density, high electromotive force, and a long charge/discharge cycle life. Recently, because of the limited capacity of carbon (graphite) anodes in Li-ion batteries, the development of alternative anode materials that are reactive with Li has been actively promoted. Among these, Si, Ge, and Sn are the most interesting materials because they have high theoretical capacities of 4,200, 1,600, and 993 mAh/g, respectively, which are much higher than the value of 372 mAh/g for conventional carbon active material. In this study, we show an method to fabricate Ge and GeSn nanostructures films for Li-ion-battery anodes with low-temperature plasma. The advantage of our process is that it allows direct fabrication of nanoparticle films on a current collector without pretreatment and temperature control by employing a simple single-step procedure [1,2]. Nanostructured Ge and GeSn films were fabricated by using He radio-frequency magnetron plasma sputtering deposition. Amorphous Ge and GeSn nanoparticles were arranged without aggregation by off-axis sputtering deposition in the high He-gas-pressure range of 0.1 Torr. The Ge film porosity was over 30%. We tested the charge/discharge cycle performance of Li-ion batteries with nanostructured Ge and GeSn anodes.The GeSn anode (3at% Sn) achieved a higher capacity of 1,128 mAh/g after 60 cycles with 92% capacity retention. Precise control of the nano-morphology and electrical characteristics by a single step procedure using low temperature plasma is effective for stable cycling of high-capacity Ge anodes. |
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