• Bulletin of the Korean Chemical Society
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• v.31 no.9
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• pp.2503-2508
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• 2010

ZnO thin films were grown on Si or $SiO_2$/Si substrates, at growth temperatures ranging from 150 to $400^{\circ}C$, by atomic layer deposition (ALD) using diethylzinc and water. Despite the large band gap of 3.3 eV, the ALD ZnO films show high n-type conductivity, i.e. low resistivity in the order of $10^{-3}\;{\Omega}cm$. In order to understand the high conductivity of ALD ZnO films, the films were characterized with X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, elastic recoil detection, Rutherford backscattering, Photoluminescence, and Raman spectroscopy. In addition, the various analytical data of the ZnO films were compared with those of ZnO single crystal. According to our analytical data, metallic zinc plays an important role for the high conductivity in ALD ZnO films. Therefore when the metallic zinc was additionally oxidized with ozone by a modified ALD sequence, the resistivity of ZnO films could be adjusted in a range of $3.8{\times}10^{-3}\;{\sim}\;19.0\;{\Omega}cm$ depending on the exposure time of ozone.

• The Korean Journal of Ceramics
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• v.6 no.3
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• pp.258-261
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• 2000

Highly (h00)-oriented (Ba, Sr)TiO$_3$(BST) thin films were grown by pulsed laser deposition on the perovskite LaNiO$_3$(LNO) metallic oxide layer as a bottom electrode. The LNO films were deposited on SiO$_2$/Si substrates by rf-magnetron sputtering method. The crystalline phases of the BST film were characterized by x-ray $\theta$-2$\theta$, $\omega$-rocking curve and $\psi$-scan diffraction measurements. The surface microsturcture observed by scanning electron microscopy was very dense and smooth. The low-frequency dielectric responses of the BST films grown at various substrate temperatures were measured as a function of frequency in the frequency range from 0.1 Hz to 10 MHz. The BST films have the dielectric constant of 265 at 1 kHz and showed multiple dielectric relaxation at the low frequency region. The origin of these low-frequency dielectric relaxation are attributed to the ionized space charge carriers such as the oxygen vacancies and defects in BST film, the interfacial polarization in the grain boundary region and the electrode polarization. We studied also on the capacitance-voltage characteristics of BST films.

• Korean Journal of Materials Research
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• v.11 no.4
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• pp.290-293
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• 2001

The SrBi$_2$Nb$_2$O$_{9}$ (SBN) thin films were deposited on p-type(100) Si substrates by rf magnetron sputtering to confirm the Possibility of Pt/SBN/Si structure for the application of nondestructive read out ferroelectric random access memory (NDRO- FRAM). The SBN thin films were deposited by co-sputtering method with Sr$_2$Nb$_2$O$_{7}$ (SNO) and Bi$_2$O$_3$ ceramic targets. The SBN thin films deposited at room temperature were annealed at $700^{\circ}C$ for 1hr in $O_2$ ambient. The structural and electrical properties of SBN with different power ratios of targets were measured by x-ray diffraction(XRD), scanning electron microscopy(SEM), capacitance-voltage(C-V), and current-voltage(I-V). The C-V curves of the SBN films showed hysteresis curves of a clockwise rotation showing ferroelectricity. When the Power ratio of the SNO/Bi$_2$O$_3$ targets was 120 W/100 W, the SBN thin films had excellent electrical properties. The memory window of SBN thin film was 1.8 V-6.3 V at applied voltage of 3 V-9 V and the leakage current density was 1.5 $\times$ 10$^{-7}$ A/$\textrm{cm}^2$ at applied voltage of 5 V The composition of SBN thin films was analysed by electron probe X-ray micro analyzer(EPMA) and the atomic ratio of Sr:Bi:Nb with pawer ratio of 120 W/100 W was 1:3:2.

• Journal of the Korean Ceramic Society
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• v.29 no.4
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• pp.328-334
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• 1992

TiO2 sols were prepared by hydrolysis and polymerization of titanium tetra-isopropoxide (TTIP) in the presence of diethanolamine (DEA). The optimal mole ratio of water to TTIP is 2 and the concentration of the TiO2 sol 0.7 M. Golden TiN films without cracks were obtained by dipping Si(110) wafers into the TiO2 sol and followed by nitridation in NH3 at 1100$^{\circ}C$ for 5 h. The TiN films were studied by an optical microscope, DTA, TGA and X-ray analysis.

• Transactions on Electrical and Electronic Materials
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• v.13 no.1
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• pp.6-9
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• 2012

In this study, we carried out an investigation of the etching characteristics (etch rate, selectivity to $SiO_2$) of ZnO thin films in $N_2/Cl_2$/Ar inductivity coupled plasma. A maximum etch rate and selectivity of 108.8 nm/min and, 3.21, respectively, was obtained for ZnO thin film at a $N_2/Cl_2$/Ar gas mixing ratio of 15:16:4 sccm. The plasmas were characterized by optical emission spectroscopy. The x-ray photoelectron spectroscopy analysis showed the efficient destruction of oxide bonds by ion bombardment. An accumulation of low volatile reaction products on the etched surface was also shown. Based on this data, an ion-assisted chemical reaction is proposed as the main etch mechanism for plasmas containing $Cl_2$.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.174-174
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• 2003

Highly (111)-oriented PZT [Pb(Zrl-xTix)O3] thin films in the Zr-rich rhombohedral phase-field were successfully fabricated on Pt(111)/Ti/SiO2/Si substrates by combining PLD method with sol-gel process. These highly (111)-oriented films can be used as model systems for polarized Raman scattering study of PZT in the rhombohedral-Phase field because the (111)-direction is the principal off-center axis of the rhombohedral ferroelectricity. For this purpose, we have fabricated PZT films employing two distinctive compositions : one with Zr/Ti = 90/10 (abbreviated as PZT90/10) and the other with Zr/Ti= 60/40 (PZT60/40). The PZT90/10 film belongs to the octahedrally distorted FR(LT) phase with a cell-doubled structure, whereas the PZT60/40 is in the high-temperature FR(HT) phase-field at room temperature. To clearly separate E(TO) phonon modes from Al(TO) modes of the (111)-oriented rhombohedral film, we have suitably devised Z(X,Y)Z and Z(X,X)Z backscattering geometries for E(TO) and Al (TO), respectively. The polarized scattering experiment demonstrated that both types of (111)-oriented rhombohedral films closely followed the Raman selection rule.

• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.57-77
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• 1998

Heteroepitaxial $Y_2O_3$ films were grown on a Si(111) substrate by ionized cluster beam deposition(ICBD) in ultra high vacuum, and its qualities such as crystllitnity, film stress, and morphological characteristics were investigated using the various measurement methods. The crystallinity was investigated by x-ray diffraction (XRD) and reflection high energy electron diffraction (RHEED). Interface crystallinity was also examined by Rutherford backscattering spectroscopy(RBS) channeling, transmission electron microscopy(TEM). The stress of the films was measured by RBS channeling and XRD. Surface and interface morphological characteristics were investigated by atomic force microscopy (AFM) and x-ray scattering method. Comparing the interface with the surface characteristics, we can conclude that many defects at the interface region were generated by interface reaction between the yttrium metal and SiO2 layer and by ion beam characteristic such as shallow implantation, so that they influenced the film qualities. The film quality was dominantly depended on the characteristic temperature range. In the temperature range from $500^{\circ}C$ to $600^{\circ}C$, the crystallinity was mainly improved and the surface roughness was drastically decreased. On the other hand, in the temperature range from $600^{\circ}C$ to $700^{\circ}C$, the compressive stress and film density were dominantly increased, and the island size was more decreased. Also the surface morphological shape was transformed from elliptical shape to triangular. The film stress existed dominantly at the interface region due to the defects generation.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.367-370
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• 2004

We fabricated PLT(5) thin film on $Pt/TiO_x/SiO_2/Si$ substrate by using sol-gel method and investigated leakage current, switching and retention properties. The leakage current density of PLT(5) thin film was $3.56{\times}10^{-7}A/cm^2$ at 4V. In the examination of switching properties, pulse voltage and load resistance were $2V{\~}5V$ and $50{\Omega}{\~}3.3k{\Omega}$, respectively. Switching time had a tendency to decrease from 520ns to 140ns with the increase of pulse voltage, and also the time was increased from 140ns to $13.7{\mu}s$ with the increase of load resistance. The activation energy obtained from the relation of applied pulse voltage and switching time was about 143kV/cm. The error of switched charge density between hysteresis loop and experiment of polarization switching was about $10\%$. Also, polarization in retention was decreased as much as about $8\%$ after $10^5$s.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.2
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• pp.43-47
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• 2003

Lead zirconate titanate (PZT) thin films were fabricated by the pulsed laser ablation deposition (PLAD) method onto Pt/Ti/SiO$_2$/Si substrates. Crystalline phases as well as preferred orientations in PZT films were investigated by X-ray diffraction analysis (XRD). The well-crystallized perovskite phase and the (101) preferred orientation were obtained by two-step annealing at the conditions of $650^{\circ}C$, 1 hour. It was found that the temperature for the pulsed laser ablated PZT films annealed via a two-step annealing process can be reduced 20$0^{\circ}C$ compared to that of the conventional three-step annealing temperature profile for enhancing the transformation of the perovskite phase. The remanent polarization and the coercive field of this film were about 20 $\mu$C/$\textrm{cm}^2$ and 46 kV/cm, while the dielectric constant and loss values measured at 1 KHz were approximately 860 and 0.04, respectively. The interesting phenomena of this film, such as vertical shift in hysteresis curve, are also discussed.

• Journal of the Korean Vacuum Society
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• v.5 no.2
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• pp.107-112
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• 1996

Thin films of $Pb(Zr_xTi_{1-x})O_3$)PZT) were grown on $Pt/SiO_2/Si(100)$ at various temperatures by RF magnetron sputtering method. Surface morphology of these films were studied by using Atomic Force Microscopy(AFM). These films were also analyzed by using Atomic Force Microscopy(AFM). These films were also analyzed by using X-ray photoemission spectroscopy(XPS) for determining their chemical composition and their depth profile. It was found that the films grown at the substrated temperature of $300^{\circ}C$ have much more smooth surface characteristics in comparison to those films grown at room temperature, which may be explained in terms of surface mobility of ad-atoms such as Pb. It was also found that Pb enrichment in the near surface region enhanced for the films grown at higher substate temperature.