A Solid-State Thin-Film Electrolyte, Lithium Silicon Oxynitride, Deposited by using RF Sputtering for Thin-Film Batteries

Dan Na,Byeongjun Lee,Baeksang Yoon,Inseok Seo 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.9

In this study, a new lithium-silicon-oxynitride (LiSiON) solid-state thin-film electrolyte was investigated for the first time. The LiSiON thin-film electrolyte was deposited by using the RF sputtering technique. In order to compare the LiSiON thin-film electrolyte to lithium phosphorous oxynitride (LiPON), a conventional thin-film electrolyte, were deposited LiPON thin-film electrolytes by using RF sputtering. Surface morphologies and cross-sectional views of the thin-film electrolytes were characterized by using field emission scanning electron microscopy (FE-SEM). The thin-films showed smooth surfaces without any cracks and pinholes. The smooth surfaces are thought to decrease the interfacial resistance between the electrolyte and the electrodes. In addition, surface morphologies were characterized by using atomic force microscopy (AFM). The sputtering rates were calculated using the thicknesses of the thin-films, as obtained from cross-sectional views. The structural properties of the thin-films were characterized using X-ray diffraction (XRD). All thin-films showed amorphous properties compared to the target material which is a crystalline material. The ionic conductivity of the LiSiON thin-film was 2.47 × 10-6 (S/cm), which is slightly higher than that of a common thin-film electrolyte LiPON.

Phase Change Induced Degradation of Amorphous Vanadium Oxide Cathode Thin Film during Charge-Discharge

Park, H.Y.,Lee, S.R.,Cho, W.I.,Kim, H.K.,Lee, S.M.,Kim, J.S.,Yoon, Y.S. 대한금속재료학회 2003 METALS AND MATERIALS International Vol.9 No.3

Amorphous vanadium oxide (V₂O_(5)) is a very good candidate as material for cathode thin film since it has a relatively high capacity. In addition, the room temperature deposition process is valuable in V₂O_(5) thin film fabrication. Due to these advantages, much effort to grow amorphous V₂O_(5) thin film has been made. In this research, we successfully grew amorphous V₂O_(5) thin film using room temperature sputtering. Based on a Li/LiPON/V₂O_(5) full cell structure, charge-discharge performances were measured according to cycling number. Even though the full cell structure showed an average capacity of 15 μAh/㎠ over more than 500 cycles, a capacity fade was shown after a few cycles. Many reports revealed that the phase change of V₂O_(5) from amorphous to crystalline made this kind of capacity fade. In order to investigate this phenomenon, high-resolution transmission electron microscopy (HRTEM) was employed. The as-deposited V₂O_(5) thin film consisted of a homogeneous amorphous without any grain-boundary and/or polycrystalline island. However, the microcrystalline V₂O_(5) phase was randomly distributed in the amorphous V₂O_(5) thin film matrix after 450 cycles by cross sectional TEM (XTEM). That is, some amorphous phase in the V₂O_(5) matrix changed to the crystalline phase. This crystalline phase strongly prevented the extraction of Li ions during the charge process, which induced the irreversible diffusion of Li ions from cathode to anode. From this result, a high efficiency thin film battery based on amorphous V₂O_(5) can be fabricated by preventing amorphous-crystal phase transformation during cycling.

박막 전지용 Pt 도핑 비정질 산화바나듐의 구조적 변화

김한기,전은정,옥영우,성태연,조원일,윤영수 한국전기전자재료학회 2000 전기전자재료학회논문지 Vol.13 No.9

The r.f. power effect for Pt doping is investigated on structural and electrochemical properties of amorphous vanadium oxide(V$_2$O$_{5}$) film, grown by direct current (d.c.) magnetron sputtering. Room temperature charge-discharge measurements based on a half-cell with a constant current clearly indicated that the Pt doping could improve the cyclibility of V$_2$O$_{5}$ cathode film. Using glancing angle x-ray diffraction(GXRD) and high-resolution transmission electron microscopy (HRTEM) analysis, we found that the Pt doping with 10W r.f. power induces more random amorphous structure than undoped V$_2$O$_{5}$ film. As the r.f. power of Pt target increases. large amount of Pt atoms incorporates into the amorphous V$_2$O$_{5}$ film and makes $\alpha$-PtO$_2$microcrystalline phase in the amorphous V$_2$O$_{5}$ matrix. These results suggest that the semiconducting $\alpha$-PtO$_2$ microcrystalline phase in amorphous matrix lead to a drastically faded cyclibility of 50W Pt doped V$_2$O$_{5}$ cathode film. Possible explanations are given to describe the Pt doping effect on cyclibillity of the amorphous V$_2$O$_{5}$ cathode film battery. film battery.

Co-Cr(-Ta)/Si 이층막의 자기적 특성

김용진,박원효,금민종,최형욱,김경환,손인환 한국전기전자재료학회 2002 전기전자재료학회논문지 Vol.15 No.3

In odder to investigate the magnetic properties of CoCr-based bilayered thin films on kind of underlayer, we introduced amorphous Si layer to Co-Cr(-Ta) magnetic layer as underlayer. First, we prepared CoCr and CoCrTa single layer using the Facing Targets Sputtering system to investigate theirs properties. It was revealed that with increasing the film thickness of CoCr, CoCrTa single layer, crystalline orientation and perpendicular coercivity was improved. The CoCrTa thin film showed bettor crystalline and magnetic characteristics than CoCr thin film. As a result of investigating magnetic properties of CoCr and CoCrTa magnetic layer on introducing the Si underlayer, perpendicular coercivity and saturation magnetization of CoCr/Si and CoCrTa/Si bilayered thin film were decreased due to the increased grain size and diffusion of Si atoms to magnetic layer. And they showed constant with increasing the film thickness of Si thin film. However, in case of CoCrTa/Si bilayered thin film, in-plane coercivity was controlled low at about 250Oe. The c-axis orientations of CoCr/si and CoCrTa/Si bilayered thin film showed a good crystalline characteristics as about $2^{\circ}$.

Thickness induced magnetic anisotropic properties of Tb-Fe-Co thin films

Yüzüak G. Durak,Yüzüak E.,Ennen I.,Hütten A. 한국물리학회 2021 Current Applied Physics Vol.29 No.-

The influence of Tb25Fe61Co14 thin film thicknesses varying from 2 to 300 nm on the structural and magnetic properties has been systematically investigated by using of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, magnetization, and magneto-optic Kerr effect microscopy measurements. Thin film growth mechanism is pursued and controlled by ex-situ X-ray refractometry measurements. X-ray diffraction studies reveal that the Tb25Fe61Co14 films are amorphous regardless of thin films thicknesses. The magnetic properties are found to be strongly related to thickness and preferred orientation. With an increase in film thickness, the easy axis of magnetization is reversed from in-plane to out-of-plane direction. The change in the easy axes direction also affects the remanence, coercivity and magnetic anisotropy values. The cause for the magnetic anisotropy direction change from in-plane to out-of-plane can be related to the preferred orientation of the thin film which depends on the large out-of-plane coercivity and plays an important role in deciding the easy axes direction of the films. According to our results, up to the 100 nm in-plane direction is dominated over the whole system under major Fe-Fe interaction region, after that point, the magnetic anisotropy direction change to the out-of-plane under major Tb-Fe/Tb-Co interaction region and preferred orientation dependent perpendicular magnetic anisotropic properties become more dominated with 2.7 kOe high coercive field values.

스퍼터링 공정 압력이 InZnO 박막트랜지스터의 광학 및 전기적 특성에 미치는 영향

박지민,김형도,장성철,김현석,Park, Ji-Min,Kim, Hyoung-Do,Jang, Seong Cheol,Kim, Hyun-Suk 한국재료학회 2020 한국재료학회지 Vol.30 No.4

Amorphous In-Ga-Zn-O (a-IGZO) thin film transistors, because of their relatively low mobility, have limits in attempts to fulfill high-end specifications for display backplanes. In-Zn-O (IZO) is a promising semiconductor material for high mobility device applications with excellent transparency to visible light region and low temperature process capability. In this paper, the effects of working pressure on the physical and electrical properties of IZO films and thin film transistors are investigated. The working pressure is modulated from 2 mTorr to 5 mTorr, whereas the other process conditions are fixed. As the working pressure increases, the extracted optical band gap of IZO films gradually decreases. Absorption coefficient spectra indicate that subgap states increase at high working pressure. Furthermore, IZO film fabricated at low working pressure shows smoother surface morphology. As a result, IZO thin film transistors with optimum conditions exhibit excellent switching characteristics with high mobility (≥ 30㎠/Vs) and large on/off ratio.

타원편광분광법 및 수소삼출법을 이용한 박막 실리콘의 증착온도 변화에 따른 미세구조 상관관계 연구

김가현 한국물리학회 2019 새물리 Vol.69 No.5

본 연구에서는 타원편광분광법 및 수소삼출법을 이용한 박막 실리콘 재료의 재료물성 분석결과를 다룬다. 비정질 실리콘 계열 박막 실리콘 재료는 결정질 실리콘과 다른 특징적 물성을 보이는데, 대표적으로재료의 밴드갭이 결정질 실리콘의 1.1 eV에 비해 광폭으로 1.7 eV 정도이며, 결정질 실리콘에 비해 높은흡광계수 및 직접천이 반도체와 같은 거동 등이 있다. 타원편광분광분석법은 시편에 조사된 빛의 편광상태변화를 관찰하는 기법으로 재료물성의 관점에서는 간접적인 분석법이다. 이를 재료에 대한 의미있는정보로 변환하기 위해서는 측정결과의 정확한 모델링이 필수적이다. 실리콘 박막의 물성 분석을 위해토크-로렌츠 분산모델(Tauc-Lorentz dispersion model)을 사용하였다. 타원편광분광법을 이용한 박막실리콘 재료의 측정결과를 토크-로렌츠 분산모델을 적용하여 분석하는 방법 및 수소삼출 실험결과와의비교를 통한 분산모델의 적정성 검증에 대한 논의를 다룬다. We analysed the material properties of thin-film silicon materials by using spectroscopic ellipsometry and hydrogen effusion. Hydrogenated amorphous silicon and the related thin film silicon material showed material properties significantly different from those of crystalline silicon, such as a wider band gap of about 1.7 eV, instead of the 1.1 eV in crystalline silicon, an elevated absorption coefficient, and characteristics of a direct bandgap. From a material point of view, an ellipsometry measurement is an indirect measurement because the result is usually given by a change in the polarization state of the probe light, so the ellipsometry measurement result must be transformed into meaningful parameters by modeling the measurement result. We used Tauc-Lorentz dispersion to model the ellipsometry measurement of the thin silicon film. In this paper, we discuss the modeling of spectroscopic ellipsometry data from thin-film silicon materials and the verification of the modeling result by using data from a complementary hydrogen effusion experiment

Spin-coating에 의한 $Ge_{20}As_{20}Se_{60}$ 비정질 chalcogenide 박막의 제조 및 광특성 분석

이강구,최세영 한국세라믹학회 2000 한국세라믹학회지 Vol.37 No.3

Amorphous Ge20As20Se60 chalcogenide thin films were prepared by spin coating technique from mixed solutions of As40Se60 and Ge40Se60 dissolved in ethylenediamine. Films were prepared at a roating speed of 3500 rpm and spinning time was 10 second and heat-treateed at 27$0^{\circ}C$ for 1 hour. The resulting film thickness and RMS roughness were approximately 340 nm and 15$\AA$. Photostructure changes were investigated with 514.5nm Ar+ laser irradiation and heat-treatment. After Ar+ laser irradiation, transmittance and transmission efficiency decreased respectively up to 24.9% at 2.43 eV and 67.5% at 3.27 eV, and absorption edge shifted toward long wavelength. Optical bandgap changed from 2.03 to 1.83 eV, and absoprtion coefficient and absorption efficiency increased up to 0.33$\times$105cm-1 at 3.37eV and 88.3% at 1.31 eV, respectively. These photodarkening state were recovered reversibly by heat-treatment at 27$0^{\circ}C$ for 1 hour. Photodarkening and thermal bleaching effects by laser irradiation and heat-treatment revealed reversible amorphous-to-amorphous transition varying only coordination number.

Pt Doping Mechanism of Vanadium Oxide Cathode Film Grown on ITO Glass for Thin Film Battery

Kim, Han-Ki,Seong, Tae-Yeon,Jeon, Eun-Jeong,Cho, Won-Il,Yoon, Young-Soo The Korean Ceramic Society 2001 한국세라믹학회지 Vol.38 No.1

An all solid-state thin film battery (TFB) was fabricated by growing, undoped and Pt-doped vanadium oxide cathode film ( $V_2$ $O_{5}$ ) on I $n_2$ $O_3$: Sn coated glass, respectively. Room temperature charge-discharge measurements based on Li/Lipon/ $V_2$ $O_{5}$ full-cell structure with a constant current clearly shows that the Pt-doped $V_2$ $O_{5}$ cathode film is superior, in terms of cyclibility. X-ray diffraction (XRD) results indicate that the Pt doping process induces a more random amorphous structure than an undoped $V_2$ $O_{5}$ film. In addition to its modified structure, the Pt-doped $V_2$ $O_{5}$ film has a smoother surface than the undoped sample. Compared to an undoped $V_2$ $O_{5}$ film, the Pt doped $V_2$ $O_{5}$ cathode film has a higher electron conductivity. We hypothesize that the addition of Pt alters electrochemical performance in a manner of making more random amorphous structure and gives an excess electron by replacing the $V^{+5}$. Possible mechanisms are discussed for the observed Pt doping effect on structural and electrochemical properties of vanadium oxide cathode films, which are grown on I $n_2$ $O_3$: Sn coated glass.

Tensile behavior of Al_1-xMo_x crystalline and amorphous thin films

Gianola, D.S.,Lee, Z.,Ophus, C.,Luber, E.J.,Mitlin, D.,Dahmen, U.,Hemker, K.J.,Radmilovic, V.R. Elsevier Science 2013 ACTA MATERIALIA Vol.61 No.5

The exceptional strength and distinct deformation physics exhibited by pure ultrafine-grained and nanocrystalline metals in comparison to their microcrystalline counterparts have been ascribed to the dominant influence of grain boundaries in accommodating plastic flow. Such grain-boundary-mediated mechanisms can be augmented by additional strengthening in nanocrystalline alloys via solute and precipitate interactions with dislocations, although its potency is a function of the changes in the elastic properties of the alloyed material. In this study, we investigate the elastic and plastic properties of Al<SUB>1-x</SUB>Mo<SUB>x</SUB> alloys (0≤x≤0.32) by tensile testing of sputter-deposited freestanding thin films. Isotropic elastic constants and strength are measured over the composition range for which three microstructural regimes are identified, including solid solutions, face-centered cubic and amorphous phase mixtures and body-centered cubic (bcc)/amorphous mixtures. Whereas the bulk modulus is measured to follow the rule of mixtures over the Mo composition range, the Young's and shear moduli do not. Poisson's ratio is non-monotonic with increasing Mo content, showing a discontinuous change at the onset of the bcc/amorphous two-phase region. The strengthening measured in alloyed thin films can be adequately predicted in the solid solution regime only by combining solute strengthening with a grain boundary pinning model. The single-step co-sputtering procedure presented here results in diversity of alloy compositions and microstructures, offering a promising avenue for tailoring the mechanical behavior of thin films.