• 한국전기전자재료학회논문지
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• 제16권8호
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• pp.716-722
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• 2003

ZnO thin films were deposited on Al and Pt electrodes by an RF reactive sputtering system for the fabrication of FBAR (film bulk acoustic wave resonator), and the effect of thermal treatment temperature on their c-axis preferred orientation was investigated. SEM experiments show that columnar structure of ZnO thin films were grown with c-axis normal to electrode material, and XRD experiments show that both ZnO films were grown with (002) plane preferred orientation, but larger diffraction peak was observed with Pt electrode. The peak intensity increased with higher thermal treatment temperature, but c-axis preferred orientation was diminished. The surface roughness of Al thin film was higher than that of Pt, and these affect the surface roughness of ZnO film deposited on the electrode. Though the preferred orientation with respect to Pt(111) plane was improved with higher thermal treatment temperature, this could not improve the c-axis orientation of ZnO film.

• 한국결정성장학회지
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• 제18권2호
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• pp.72-75
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• 2008

Zinc oxide (ZnO) thin films were prepared by a sol-gel method. The structural and electrical properties were investigated by varying drying and annealing temperatures. The thin films were coated (250 nm) by spin-coating method on glass substrates. The optimum drying temperature of ZnO thin films was 300$^{\circ}C$ where the resistivity was the lowest and the preferred c-axis orientation was the highest. The annealing was carried out in air and inert atmospheric conditions. The degree of the preferred c-axis orientation was estimated. The highest preferred c-axis orientation was recorded at 600$^{\circ}C$. The preferred c-axis orientation and grain growth resulted in the mobility enhancement of the ZnO thin films, and the lowest resistivity was 0.62${\Omega}{\cdot}cm$ at 600$^{\circ}C$.

• 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.

• 대한금속재료학회지
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• 제50권1호
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• pp.78-85
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• 2012

Aluminum nitride(AlN) is a compound (III-V group) of hexagonal system with a crystal structure. Its Wurzite phase is a very wide band gap semiconductor material. It has not only a high thermal conductivity, a high electrical resistance, a high electrical insulating constant, a high breakdown voltage and an excellent mechanical strength but also stable thermal and chemical characteristics. This study is on the preferred orientation characteristics of AlN thin films by reactive evaporation using $NH_3$. We have manufactured an AlN thin film and then have checked the crystal structure and the preferred orientation by using an X-ray diffractometer and have also observed the microstructure with TEM and AlN chemical structure with FT-IR. We can manufacture an excellent AlN thin film by reactive evaporation using $NH_3$ under 873 K of substrate temperature. The AlN thin film growth is dependent on Al supplying and $NH_3$ has been found to be effective as a source of $N_2$. However, the nuclear structure of AlN did not occur randomly around the substrate a particle of the a-axis orientation in fast growth speed becomes an earlier crystal structure and is shown to have an a-axis preferred orientation. Therefore, reactive evaporation using $NH_3$ is not affected by provided $H_2$ amount and this can be an easy a-axis orientation method.

• 한국재료학회지
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• 제25권3호
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• pp.138-143
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• 2015

Aluminum nitride, a compound semiconductor, has a Wurtzite structure; good material properties such as high thermal conductivity, great electric conductivity, high dielectric breakdown strength, a wide energy band gap (6.2eV), a fast elastic wave speed; and excellent in thermal and chemical stability. Furthermore, the thermal expansion coefficient of the aluminum nitride is similar to those of Si and GaAs. Due to these characteristics, aluminum nitride can be applied to electric packaging components, dielectric materials, SAW (surface acoustic wave) devices, and photoelectric devices. In this study, we surveyed the crystallization and preferred orientation of AlN thin films with an X-ray diffractometer. To fabricate the AlN thin film, we used the magnetron sputtering method with $N_2$, NH3 and Ar. According to an increase in the partial pressures of $N_2$ and $NH_3$, Al was nitrified and deposited onto a substrate in a molecular form. When AlN was fabricated with $N_2$, it showed a c-axis orientation and tended toward a high orientation with an increase in the temperature. On the other hand, when AlN was fabricated with $NH_3$, it showed a-axis orientation. This result is coincident with the proposed mechanism. We fabricated AlN thin films with an a-axis orientation by controlling the sputtering electric power, $NH_3$ pressure, deposition speed, and substrate temperature. According to the proposed mechanism, we also fabricated AlN thin films which demonstrated high a-axis and c-axis orientations.

• 한국진공학회지
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• 제15권6호
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• pp.619-623
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• 2006

FBAR(Film Bulk Acoustic Resonator) 소자의 공진특성을 결정하는 가장 중요한 요소는 압전막의 압전성을 들 수 있다. FBAR 압전막으로 유력한 ZnO 압전박막은 (002)면 c-축 우선배향성(preferred orientation)의 정도에 따라서 압전성이 결정된다. 그러므로 ZnO 박막의 우선배향성에 관한 연구는 많은 연구자들의 관심사가 되어왔다. 본 논문에서는 ZnO 보조씨드충(helped seed layer)을 이용하여 ZnO 압전박막의 우선배향성에 대하여 조사하였으며, rocking curve의 표준편차$(\sigma)$ 값이 $1.15^{\circ}$인 주상형 결정립을 가진 c-축 ZnO 압전박막이 우수한 압전특성을 나타내는 것을 확인하였다.

• 한국세라믹학회지
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• 제42권11호
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• pp.763-769
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• 2005

Ferroelectric $ReMnO_3$(Re:Ho, Er) thin films were deposited on Si(100) substrate by Metal-Organic Chemical Vapor Deposition (MOCVD). Crystallinity and electric properties of $ReMnO_3$(Re:Ho, Er) thin films were investigated as a function of thermal heat treatment process, CHP (Conventional Heat-treatment Process) and RTP (Rapid Thermal Process). $ReMnO_3$(Re:Ho, Er) thin films prepared by RTP showed higher c-axis preferred orientation and homogeneous surface roughness than those prepared by CHP. The remnant polarization of ferroelectric hysteresis loop of $ReMnO_3$(Re:Ho, Er) thin films was strongly dependent on the c­axis preferred orientation of hexagonal single phase, and the leakage current characteristics of thin films were dependent on the homogeneity of grain size as well as surface roughness of thin films.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.246-250
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• 2000

Reactive radio frequency (RF)magnetron sputter has been used to deposit AlN thin film on a Si substrate. (002)Preferred orientation of AlN thin film has been obtained at low sputtering pressure and high $\textrm{N}_2$ concentration. Also it has been shown that properties of AlN thin film are affected by presputtering time. As presputtering time increased aluminum and nitride concentration of AlN thin film decreased. But oxygen concentration and grain size increased. The good preferred orientation was shown with the short presputtering time.

• Journal of information and communication convergence engineering
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• 제3권3호
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• pp.131-136
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• 2005

The effects of the deposition temperature on the growth characteristics of the ZnO films were studied for film bulk acoustic wave resonator (FBAR) device applications. All films were deposited using a radio frequency (RF) magnetron sputtering technique. It was found that the growth characteristics of the ZnO films have a strong dependence on the deposition temperature from 25 to $350^{\circ}C$. The ZnO films deposited below $200^{\circ}C$ exhibited reasonably good columnar grain structures with a highly preferred c-axis orientation while those above 200°C showed very poor columnar grain structures with a mixed-axis orientation. This study seems very useful for the future FBAR device applications.

• E2M - 전기 전자와 첨단 소재
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• 제9권2호
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• pp.196-203
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• 1996

The highly c-axis oriented zinc oxide thin films were deposited on Sapphire(0001) substrates by reactive RF magnetron sputtering. The characteristics of zinc oxide thin films on RF power, substrate-target distance, and substrate temperature were investigated by XRD, SEM and EDX analyses. The physical characteristics of zinc oxide thin films changed with various deposition conditions. The higher substrate temperatures were, The better crystallinity of zinc oxide thin films. The highly c-axis oriented zinc oxide thin films were obtained at sputter pressure 5mTorr, rf power 200W, substrate temperature 350.deg. C, substrate-target distance 5.5cm. In these conditions, the resistivity of zinc oxide thin films deposited on pt/sapphire was 12.196*10$^{9}$ [.ohm.cm].