• Journal of the Korean Ceramic Society
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• v.37 no.7
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• pp.665-672
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• 2000

The ferroelectric YMnO3 thin films were prepared by MOD(metal-organic decomposition) method with Y- and Mn-acetylacetonate as starting materials. Thin films were grown on various substrates by spin-coating technique. The crystalline phases of the thin films were identified by X-ray diffractometer as a function of heat-treatment temperature, pH of coating solution and substrate. In addition, the effect of Mn/Y molar ratio(0.8~1.2) on the formation of hexagonal-YMnO3 phase was investigated. In forming highly c-axisoriented hexagonal-YMnO3 single phase, the Pt coated Si substrate was more effective than the bare Si substrate, and the optimum heat-treatment condition was at 82$0^{\circ}C$ for 30 min. Higher Mn/Y molar ratio within 0.8~1.2 and pH of YMnO3 precursor solution within 0.5~2.5 favored formation of ferroelectric hexagonal phase rather than orthorhombic phase. Leakage current density of the hexagonal-YMnO3 thin film formed on Pt(111)/TiO2/SiO2/Si substrate was low enough as 0.4~4.0$\times$10-8(A/$\textrm{cm}^2$) at 5 V and its remanent polarization(Pr), calculated from the P-E hysteresis loop, was 3 nC/$\textrm{cm}^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.456-459
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• 2000

Thin films of vanadium oxide(V$O_x$) have been deposited by r.f. magnetron sputtering from $V_2$$O_5$ prget in gas mixture of argon and oxygen. Crystal structure, surface morphology, chemical composition and bonding properties of films in-situ annealed in $O_2$ ambient with various heat-treatment conditions are characterized through XRD, SEM, AES, RBS and FTIR measurements. The filrns annealed below 200 $^{\circ}C$are amorphous, and those annealed above 30$0^{\circ}C$ are polycrystalline. The growth of grains and the transition of vanadium oxide into the higher oxide have been obsenred with increasing the annealing temperature and time. The increase of O/V ratio with increasing the annealing temperature and time is attributed to the diffusion of oxygen and the partial filling of oxygen vacancies. It is observed that the oxygen atoms located on the V-0 plane of $V_2$$O_5$ layer participate more readily in the oxidation process.

• Journal of the Korean Ceramic Society
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• v.40 no.2
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• pp.184-190
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• 2003

$Sr_{0.9}Bi_{2.1}Ta_2O_9$thin films were deposited on $IrO_2$ electrode by spin coating method using photosensitive sol-gel solution. To ensure the UV-exposure effect on SBT thin films, UV irradiated films and non-UV irradiated films were analyzed by XRD, SEM. As a result, UV-irradiation on SBT thin films promoted grain growth of SBT compared with no UV irradiation. In case of the UV irradiated films annealed at$740{\circ}C$for 1 h in an oxygen ambient, the 2Pr value and Pr/Ps at${pm}5$V were$11.48{mu}C/cm^2$and 0.53, respectively. 2Pr values of the UV irradiated SBT thin films at$660-740{circ}C were approximately 12% higher than those of non-UV irradiated thin films.

• Transactions on Electrical and Electronic Materials
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• v.10 no.3
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• pp.89-92
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• 2009

High-quality Al-N doped p-type ZnO thin films were deposited on Si and buffer layer/Si by DC magnetron sputtering in a mixture of $N_2$ and $O_2$ gas. The target was ceramic ZnO mixed with $Al_2O_3$ (2 wt%). The p-type ZnO thin films showed a carrier concentration in the range of $1.5{\times}10^{15}{\sim}2.93{\times}10^{17}\;cm^{-3}$, resistivity in the range of 131.2${\sim}$2.864 ${\Omega}cm$, mobility in the range of 3.99${\sim}$31.6 $cm^2V^{-1}s^{-l}$, respectively. It was easier to dope p-type ZnO films on Si substrates than on buffer layer/Si. The film grown on Si showed the highest quality of photoluminescence (PL) characteristics. The Al donor energy level depth $(E_d)$ of Al-N codoped ZnO films was reduced to about 50 meV, and the N acceptor energy level depth $(E_a)$ was reduced to 63 meV.

• Korean Journal of Materials Research
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• v.12 no.5
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• pp.382-386
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• 2002

We studied growth and characterization of $SrBi_2Ta_2O_9$ (SBT) thin films fabricated by low temperature process under vacuum and/or oxygen ambient. A metal organic decomposition (MOD) method based on a spin-on technique and annealing process using a rapid thermal annealing (RTA) method was used to prepare the SBT films. The crystallinity of a ferroelectric phase of SBT thin films is related to the oxygen partial pressure during RTA process. Under an oxygen partial pressure higher than 30 Torr, the crystallization temperature inducing the ferroelectric SBT phase can be lowered to $650^{\circ}C$. Those films annealed at $650^{\circ}C$ in vacuum and oxygen ambient showed good ferroelectric properties, that is, the memory window of 0.5~0.9 V at applied voltage of 3~7 V and the leakage current density of 1.80{\times}10^{-8}$ A/$\textrm{cm}^2$ at an applied voltage of 5V. In comparison with the SBT thin films prepared at 80$0^{\circ}C$ in $O_2$ ambient by furnace annealing process, the SBT thin films prepared at $650^{\circ}C$ in vacuum and oxygen ambient using the RTA process showed a good crystallization and electrical properties which would be able to apply to the virtul device fabrication precess.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.229-233
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• 2019

Pure $BiFeO_3$ (BFO) and (Eu, V) co-doped $Bi_{0.9}Eu_{0.1}Fe_{0.975}V_{0.025}O_{3+{\delta}}$ (BEFVO) thin films were deposited on $Pt(111)/Ti/SiO_2/Si(100)$ substrates by chemical solution deposition. The effects of co-doping were observed by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). The electrical properties of the BEFVO thin film were improved as compared to those of the pure BFO thin film. The remnant polarization ($2P_r$) of the BEFVO thin film was approximately $26{\mu}C/cm^2$ at a maximum electric field of 1,190 kV/cm with a frequency of 1 kHz. The leakage current density of the co-doped BEFVO thin film ($4.81{\times}10^{-5}A/cm^2$ at 100 kV/cm) was two orders of magnitude lower than of that of the pure BFO thin film.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.377-380
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• 2001

The BST thin films to composite (Ba$\sub$x/Sr$\sub$l-x/)TiO$_3$ using sol-gel method were fabricated on Pt/Ti/SiO$_2$/Si substrate. The thin film capacitor to be ferroelectric materials was investigated by structural and electrical properties. BST solution was composited by moi ratio, and then spin-coated (from 3 times to 5 times coating on Pt/SiO$_2$/Si substrate. Thickness of BST ceramics thin films are about 2600∼2800[${\AA}$] in 3 times deposition. The property of leakage current was stable when the applied voltage was 3[V]. Leakage current of 3 times coated BST thin film was 10$\^$-9/∼10$\^$-11/[A] at 0∼3[V].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.352-355
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• 2003

[ $Bi_{3.25}La_{0.75}Ti_3O_{12}$ ] (BLT) thin films were prepared by using metal organic decomposition method onto the LaNiO3 (LNO) bottom electrode. Both the structure and morphology of the films were analyzed by x-ray diffraction (XRD) and atomic force microscope (AFM). Even at low temperatures ranging from 450 to $650^{\circ}C$, the BLT thin films were successfully deposited on LNO bottom electrode and exhibited (117) orientation. The BLT thin films annealed as low as $600^{\circ}C$ showed excellent ferroelectricity, higher remanent polarization and no significant degradation of switching charge at least up to $5{\times}10^9$ switching cycles at a frequency of 100 kHz and 5 V. For the annealing temperature of $600^{\circ}C$, the remanent polarization $P_r$ and coercive field were $23.5\;{\mu}C/cm^2$ and 120 kV/cm, respectively.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1351_1352
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• 2009

We deposited $SnO_2$:F thin films by atomospheric pressure chemical vapor deposition(APCVD) on corning glass. $SnO_2$:F films were used as transparent conductive oxide (TCO) electrode for Si thin film solar cells. We have investigated structural, electrical and optical properties of $SnO_2$:F thin films and fabricated thin film Si solar cells by plasma enhanced CVD(PECVD) on $SnO_2$:F thin films The cells were characterized by I-V measurement using AM1.5 spectra. Conversion efficiency of our cells were between 5.61% and 6.45%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.235-238
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• 1998

Ferroelectric $LiNbO_3$ thin films were grown directly on Si(100) substrates by 13.55MHz RF magnetron sputtering system using a ceramic target ($Nb_2O_5/Li_2C0_3$ = 51.4/48.6). Because high temperature process have to avoided to prevent degradation of the interface (insulator/Si), $LiNbO_3$ thin films were deposited below $300^{\circ}C$. After as-deposited films were performed RTA treatments in an oxygen ambient at $600^{\circ}C$ for 60s, electrical measurements performed films before and after anneal treatment. In high field region, the leakage current density of the films after annealing was deceased about 4order and the resistivity of these was increased to about 5\times 10^{11} \Omega \cdot cm$ at 500kV/cm. In accumulation region of C-V curve, we calculated dielectric constant of thin film $LiNbO_3$ as 27.9 which is close to that of bulk value.