• ETRI Journal
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• 제18권4호
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• pp.339-346
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• 1997

Good quality a-axis oriented thin films of $YBa_2Cu_3O_{7-x}$ may be grown by the use of a $PrBa_2Cu_3O_{7-x}$ (PBCO) layer as a template. Here we present a detailed study of the nucleation of the PBCO layer, explaining the orientations observed. It is determined that the wavy surface of a $LaSrGaO_4$ (LSGO) (100) substrate consists of the {101} planes by observing cross-sectional transmission electron microscopy images of the interface between the PBCO film and the substrate. The images and selected area diffraction patterns show that a mixed c-and b-axis oriented PBCO layer was initially grown on the substrate, followed by pure b-axis oriented PBCO growth. We explain that the c-axis oriented growth is the result of the growth of the PBCO (019) planes on the LSGO (101) planes. We conclude that the nucleation and growth of the PBCO films at the initial stages depends on the crystallographic plane of the substrate surfaces, however, as the film grows further, the kinetics of the deposition process favors b-axis oriented growth.

• 한국세라믹학회지
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• 제35권10호
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• pp.1107-1112
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• 1998

We could obtan c-axis oriented $SrBi_2$$Ta_2$$O_9$ thin films on usual Pt(111)/Ti/$SiO_2$/Si(100) substrate using a r. f. magnetron sputtering technique. According to the increase of sputtering pressure from 250 to 300 mTorr the Bi content and degree of the c-a xis preferred orientation of $SrBi_2$$Ta_2$$O_9$ thin films were increased. By controlling Bi(or $Bi_2O_3$) loss from $SrBi_2$$Ta_2$$O_9$ thin films during post annealing and by inserting $Bi_2O_3$ layer in $SrBi_2$$Ta_2$$O_9$ thin films the effect of Bi content on the c-axis oriented growth of $SrBi_2$$Ta_2$$O_9$ thin films could be investigated without the effect of sputtering pressure. The degree of the c-axis preferred orientation of $SrBi_2$$Ta_2$$O_9$ thin films was increased with increasing with increasing Bi content by control of Bi(or $Bi_2O_3$) loss of $SrBi_2$$Ta_2$$O_9$ thin films. But the c-axis oriented growth of $SrBi_2$$Ta_2$$O_9$ thin films disappeared by the inserting of $Bi_2O_3$ lay-er in $SrBi_2$$Ta_2$$O_9$ thin films.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.51-55
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• 2000

Using modified melt-textured grown targets, YBa$_2$Cu$_3$O$_{7-{\delta}}$ thin films were prepared by pulsed laser deposition technique at the laser energy density from 1 J/cm$_2$ to 4 J/cm$_2$. All the films showed c-axis preferred orientations, however, a-axis outgrowths on the film surface were considerably increased with an increase of the laser energy density. To examine the origin of the a-axis outgrowth formation, the microstructures of films deposited at 2 J/cm$_2$ and 4 J/cm$_2$ were investigated using X-ray diffraction, transmission electron microscopy, and high-resolution electron microscopy. It was shown that a significant number of Y$_2$O$_3$ inclusions were formed during the growth of c-axis oriented films at 4 J/cm$_2$. These inclusions formed nucleation sites for the a-axis outgrowths. It is considered that, due to the unstable growth conditions with a high flux density of incident vapor species and the strain induced by the surrounding c-axis films, the Y$_2$O$_3$ inclusions would prefer the nucleation of α-axis grains.

• The Korean Journal of Ceramics
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• 제6권2호
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• pp.116-119
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• 2000

The a-axis and c-axis prefer oriented SBT thin films could be deposited on Pt(111)/Ti/$SiO_2$$650^{\circ}C$). The c-axis preferred orientation of SBT film can be obtained by Sr deficiency and high compressive stress. However, the a-axis-oriented grains can be formed under stoichiometric Sr content and nearly stress-free state.

• Progress in Superconductivity
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• 제11권2호
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• pp.141-146
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• 2010

Phase stability diagram and boundary of a- and c-axis orientation of $SmBa_2Cu_3O_{7-y}$ (SmBCO) thin films grown by pulsed laser deposition (PLD) were reported with studies based on x-ray diffraction [1]. Four different samples are systematically analyzed: normal c-axis oriented orthorhombic $SmBa_2Cu_3O_{7-y}$, a-axis oriented $SmBa_2Cu_3O_{7-y}$, c-axis oriented orthorhombic $SmBa_2Cu_3O_{7-y}$ with $Sm_2BaCuO_5$ phase, and a mixture with c-axis oriented orthorhombic $SmBa_2Cu_3O_{7-y}$ and anomalously long-c tetragonal $SmBa_2Cu_3O_x$. Raman scattering spectroscopy equipped with polarization analysis elucidates the crystal orientation and the origin of the growth of the materials. It indicates that the technique can be used for quality control of conductor manufacturing processes as well as for enhancement of the materials properties.

• 한국세라믹학회지
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• 제35권7호
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• pp.733-739
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• 1998

C-axis oriented zinc oxide thin films were deposited on Cornign 1737 glass substrate by an rf magnetron sputtering technique. The effects of deposition parameters and post heat-treatment on the crystallinity and electical properties of ZnO films were investigaed. As-deposited ZnO films showed the strong c-axis growth and excellent crystallinity under the deposition conditions as follows: substrate temperature 350$^{\circ}C$ ; growth and excellent crystallinity under the deposition conditions as follows ; substrate temperature 350$^{\circ}C$ rf power 75W ; gas pressure 6m Torr; percentage of oxygen 50% The higher heat-treating temperatue was the stronger c-axis growth and the better crystallinity of the deposited ZnO films were. The resistivity of ZnO films was significantly affected by deposition parameters and post heat-treatment. With increasing increased. After post heat-treating at 400$^{\circ}C$ in air the resistivity of ZnO films increased but post heat-treat-ing temperature 500$^{\circ}C$ rather diminished the film resistivity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.256-256
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• 2008

We report epitaxial growth of ZnO thin films on (100) single-crystalline $LaAlO_3$ (LAO) substrates using pulsed laser deposition (PLD) at different substrate temperatures (400~$800^{\circ}C$). The structural and electrical properties of the films have been investigated by means of X-ray diffraction (XRD), atomic force microscope (AFM), transmission line method (TLM). The poly-crystalline of $\alpha$- and c-axis oriented ZnO film was formed at lower deposition temperature ($T_s$) of $400^{\circ}C$. At higher $T_s$, however, the films exhibit single-crystalline of $\alpha$-axis orientation represented by ZnO[$\bar{1}11$ || LAO <001>. The electrical properties of ZnO thin films depend upon their crystalline orientation, showing lower electrical resistivity values for $\alpha$-axis oriented ZnO films.

• The Korean Journal of Ceramics
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• 제3권4호
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• pp.257-262
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• 1997

Aluminum nitride(AIN) thin films were deposited on SiO$_2$/Si substrates by reactive sputtering for the application of SAW devices. The major deposition parameters such as pressure, nitrogen fraction, rf power, substrate distance were changed to find out the optimal condition for c-axis oriented thin films on an amorphous substrate. The effects of deposition parameters on the crystal structure, residual stress, and growth morphology of thin films were characterized by XRD, SEM, and TEM. The FWHM of (002) rocking curve of the films deposited at the proper condition was lower than 2.2$^{\circ}$(C=0.93$^{\circ}$). Cross-sectional TEM showed that self-aligned structure was developed just after slightly random growth at the initial stage. The frequency characteristics of test device fabricated from AIN thin films confirmed their piezoelectric property and applicability for SAW devices.

• 멤브레인
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• 제28권5호
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• pp.340-350
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• 2018

본 연구에서는 바늘형 종결정 코팅 양을 조절함으로써 결정학적으로 b-축 그리고 c-축으로 배향된 모데나이트(MOR) 제올라이트 분리막을 제조하고 결정학적 배향이 투과증발 에탄올 탈수 거동에 미치는 영향을 고찰하였다. c-축으로 배향된 종결정의 코팅 양이 증가할수록 b-축에서 c-축으로 배향된 분리막이 얻어졌고 이는 진화론적 성장으로 설명되었다. b-축 방향으로 배향된 분리막의 경우 1000 이상의 높은 선택도와 $0.2kg/m^2h$의 총 투과도를 나타내었으며 c-축 배향된 분리막 보다 우수한 분리성능을 나타내었다. 이는 물의 운동역학적 직경이 b-축 방향으로 단일 존재하는 8R 기공채널의 직경에 비하여 작기 때문에 물의 이동이 방해되지 않는 반면 에탄올은 상대적으로 방해받기 때문으로 설명되었다. 따라서 본 연구로부터 바늘형 종결정 코팅 양을 조절함으로써 모데나이트 분리층의 결정학적 배향을 조절할 수 있었고, b-축으로 배향된 모데나이트 분리막이 보다 우수한 투과증발 에탄올 탈수 거동을 보임을 확인할 수 있었다.

• The Korean Journal of Ceramics
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• 제6권2호
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• pp.110-115
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• 2000

$SrBi_2Ta_2O_9$ thin films were deposited at room temperature on the usual (111) oriented Pt bottom electrodes using r.f. magnetron sputtering, and then post-annealed at 650-$800^{\circ}C$ for 30min in oxygen flow. Low temperature processing which shows the preferred oriented SBT thin films was obtained by controlling the sputtering pressure and/or Sr content in target. The orientation and grain growth behavior of SBT thin films were dependent on Sr contents in films. With increasing the excess Bi content up to 50% in SBT thin films, it was possible to lower the onset temperature of grain growth. The c-axis preferred oriented SBT thin films were well-grown under the condition of low post-annealing($650^{\circ}C$) by lowering post-annealing pressure. After $10^{11}$ switching cycles, no polarization degradation was observed in both preferred oriented SBT capacitors.