• Korean Journal of Materials Research
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• v.7 no.12
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• pp.1077-1082
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• 1997

TiN은 기상반응법으로 티타늄판과 질소가스의 질화반응에 의해 제조되었다. $\delta$-TiN은 약 1100-140$0^{\circ}C$의 온도 범위에서만 형성되는데 반해, 110$0^{\circ}C$이하의 온도에서는 $\varepsilon$-TiN 상도 관찰할 수 있었다. $\delta$-TiN의 미소정도값은 3000$\pm$300kg/m$m^2$였고, 격자상수는 0.4226$\mu\textrm{m}$였다. 가스의 유동속도가 0.7$\ell$/min의 속도이하에서는 확산과정에 의해 지배됨을 알 수 있었다. 활성화에너지가 110$0^{\circ}C$이상에서는 67.6Kcal/mol이었고 110$0^{\circ}C$이상에서는 13.9Kcal/mol이었던 것으로 보아 반응메커니즘이 110$0^{\circ}C$를 기점으로 변한다는 것을 명백히 관찰할 수 있었다. 그리고 증착속도가 확산과정에 의해 지배되는 영역에서 TiN의 증착속도는 전체 유량의 제곱근에 비례하였다.

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.234-240
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• 2001

The diffusion barrier properties of TiN by using Cu(Mg) alloy film have been investigated. Cu(Mg) alloy film was deposited on air-exposed TiN film. Upon annealing, interfacial MgO of 100 $\AA$ has been formed due to the reaction of Mg with oxygen existed on the surface of TiN. Combined MgO/TiN structure prevented the interdiffusion of Cu and Si up to $800^{\circ}C$. To improve the adhesion of Cu(Mg) alloy film to the TiN, TiN layer was treated by $O_2$ plasma, followed by vacuum annealing at $300^{\circ}C$. It was found that increased oxygen on the surface of TiN film by plasma treatment enhanced segregation of Mg toward the interface, resulting in the formation of dense MgO layer. Improved adhesion characteristics have been formed through this treatment. However, increased power of $O_2$ plasma led to the formation of TiO$_2$ and decreased the Mg content to be segregated to the interface, resulting in the decrease in adhesion property. In addition, the deposition of 50 ${\AA}$ Si on the TiN enhanced the adhesion of Cu(Mg) alloy to TiN without deteriorating the TiN diffusion barrier characteristics.

• Korean Journal of Materials Research
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• v.10 no.1
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• pp.90-96
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• 2000

The effects of the type and thickness of underlayers on the crystallographic texture and the sheet resistance of aluminum thin films were studied. Sputtered Ti and Ti/TiN were examined as the underlayer of the aluminum films. The texture and the sheet resistance of the metal thin film stacks were investigated at various thicknesses of Ti or TiN, and the sheet resistance was measured after annealing at $400^{\circ}C$ in an nitrogen ambient. For the Ti underlayer, the minimum thickness to obtain excellent texture of aluminum <111> was 10nm, and the sheet resistance of the metal stack was greatly increased after annealing due to the interdiffusion and reaction of Al and Ti. TiN between Ti and Al could suppress the Al-Ti reaction, while it deteriorated the texture of the aluminum film. For the Ti/TiN underlayer, the minimum Ti thickness to obtain excellent texture of aluminum <111> was 20nm, and the minimum thickness of TiN to function as a diffusion barrier between Ti and Al was 20nm.

• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1129-1136
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• 1999

TIN films were prepared on Si(100) substrate by ICP-CVD(inductive1y coupled plasma enhanced chemical vapor deposition) using TEMAT(tetrakis ethylmethamido titanium : Ti$[\textrm{N}\textrm{(CH)}_{3}\textrm{C}_{2}\textrm{H}_{5}]_{4}$) precursor at various deposition conditions. Phase, microstructure, and the electrical properties of TIN films were characterized by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM) and electrical measurements. Polycrystalline TiN films with B1 structure were grown at temperatures over $200^{\circ}C$. Preferentially oriented along TiN(111) films were obtained at temperatures over $300^{\circ}C$ with the flow rates of 10, 5, and 5 sccm for TEMAT, $\textrm{N}_{2}$ and Ar gas. The TiN/Si(100) interface was flat and no chemical reaction between TIN and $\textrm{SiO}_2$ was found. The resistivity, carrier concentration and the carrier mobility for the TiN sample prepared at $500^{\circ}C$ are 21 $\mu\Omega$cm, 9.5$\times\textrm{10}^{18}\textrm{cm}^{-3}$ and $462.6\textrm{cm}^{2}$/Vs, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.266-267
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• 2011

질화갈륨(GaN)은 높은 전자이동도 및 높은 항복전계를 가지며 낮은 온저항으로 인하여 에너지효율이 우수하기 때문에 고출력 전력소자 분야에서 많은 관심을 받고 있다. GaN을 이용한 고출력 전력소자의 경우 상용화 수준에 근접할 만한 기술적 진보가 있었으나, 페르미 레벨 고정(Fermi-level pinning) 현상, 소자의 누설전류 등 아직 해결되어야 할 문제를 갖고 있다. 본 연구에서는 실리콘 기판 위에 성장된 GaN 에피탁시를 활용한 고출력 전력소자의 누설전류를 억제시키기 위해 오믹 접합 중 Au의 상호확산을 억제하는 중간층 금속(Mo or Ni)을 변화시켰으며 오믹 열처리 온도에 따른 특성을 비교 연구하였다. $Cl_2$와 $BCl_3$를 이용하여 0.6 ${\mu}m$ 깊이의 메사 구조가 활성영역을 형성하였고, Si 도핑된 n-GaN 위에 Ti/Al/Mo/Au (20/100/25/200 nm) 와 Ti/Al/Ni/Au (20/100/25/200 nm) 오믹 접합을 각각 설계, 제작하였다. 오믹 열처리시의 GaN 표면오염을 방지하기 위해 $SiO_2$ 희생층을 증착하였다. 오믹 접합 형성을 위해 각 750$^{\circ}C$, 800$^{\circ}C$, 850$^{\circ}C$에서 30초간 열처리를 진행 하였으며, 이후 6 : 1 BOE 용액으로 $SiO_2$ 희생층을 제거하였다. 750, 800, 850$^{\circ}C$에서 Ti/Al/Mo/Au 구조의 오믹 접합 저항은 각 2.56, 2.34, 2.22 ${\Omega}$-mm 이었으며, Ti/Al/Ni/Au 구조의 오믹 접합 저항은 각 43.72, 2.64, 1.86 ${\Omega}$-mm이었다. Isolation 누설전류를 측정하기 위해서 두 개의 오믹 접합 사이에 메사 구조가 있는 테스트 구조를 제안하였다. Isolation 누설전류는 Ti/Al/Mo/Au 구조에서 두 오믹 접합 사이의 거리가 25 ${\mu}m$이고 100 V일 때 750, 800, 850 $^{\circ}C$의 열처리 온도에서 각 1.25 nA/${\mu}m$, 2.48 nA/${\mu}m$, 8.76 nA/${\mu}m$이었으며, Ti/Al/Ni/Au 구조에서는 각 1.58 nA/${\mu}m$, 2.13 nA/${\mu}m$, 96.36 nA/${\mu}m$이었다. 열처리 온도가 증가하며 오믹 접합 저항은 감소하였으나 isolation 누설전류는 증가하였다. 750$^{\circ}C$ 열처리에서 오믹 접합 저항은Ti/Al/Mo/Au 구조가 Ti/Al/Ni/Au 구조보다 약 17배 우수하였고, 850$^{\circ}C$ 고온의 열처리 경우 Ti/Al/Mo/Au 구조의 isolation 누설전류는 8.76 nA/${\mu}m$로 Ti/Al/Ni/Au의 누설전류 96.36 nA/${\mu}m$보다 약 11배 우수하였다. Ti/Al/Mo/Au가 Ti/Al/Ni/Au 보다 오믹 접합 저항과 isolation 누설전류 측면에서 전력용 GaN 소자에 적합함을 확인하였다.

• Journal of Environmental Science International
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• v.17 no.8
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• pp.933-941
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• 2008

The formation of $Co_nTiO_{n+2}$ compounds, i.e., $CoTiO_3$ and $CO_2TiO_4$, in a 5wt% $CoO_x/TiO_2$ catalyst after calcination at different temperatures has been characterized via scanning electron microscopy (SEM), Raman and X-ray photoelectron spectroscopy (XPS) measurements to verify our earlier model associated with $CO_3O_4$ nanoparticles present in the catalyst, and laboratory-synthesized $Co_nTiO_{n+2}$ chemicals have been employed to directly measure their activity profiles for CO oxidation at $100^{\circ}C$. SEM measurements with the synthetic $CoTiO_3$ and $CO_2TiO_4$ gave the respective tetragonal and rhombohedral morphology structures, in good agreement with the earlier XRD results. Weak Raman peaks at 239, 267 and 336 $cm^{-1}$ appeared on 5wt% $CoO_x/TiO_2$ after calcination at $570^{\circ}C$ but not on the catalyst calcined at $450^{\circ}C$, and these peaks were observed for the $Co_nTiO_{n+2}$ compounds, particularly $CoTiO_3$. All samples of the two cobalt titanate possessed O ls XPS spectra comprised of strong peaks at $530.0{\pm}0.1$ eV with a shoulder at a 532.2-eV binding energy. The O ls structure at binding energies near 530.0 eV was shown for a sample of 5 wt% $CoO_x/TiO_2$, irrespective to calcination temperature. The noticeable difference between the catalyst calcined at 450 and $570^{\circ}C$ is the 532.2 eV shoulder which was indicative of the formation of the $Co_nTiO_{n+2}$ compounds in the catalyst. No long-life activity maintenance of the synthetic $Co_nTiO_{n+2}$ compounds for CO oxidation at $100^{\circ}C$ was a good vehicle to strongly sup port the reason why the supported $CoO_x$ catalyst after calcination at $570^{\circ}C$ had been practically inactive for the oxidation reaction in our previous study; consequently, the earlier proposed model for the $CO_3O_4$ nanoparticles existing with the catalyst following calcination at different temperatures is very consistent with the characterization results and activity measurements with the cobalt titanates.

• Journal of the Korean Ceramic Society
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• v.35 no.11
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• pp.1130-1140
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• 1998

Thin films of $Bi_4Ti_3O_{12}\;nBaTiO_3(n=1&2)$ were prepared using sols erived Ba-Bi-Ti complex alkoxides. The sols were spin-cast onto $Pt/Ti/SiO_2/Si$ substrates and followed by pyrolysis for 1 hr at $620^{\circ}C,\;700^{\circ}C\;and\;750^{\circ}C$ In the thin films a pyrochlore phase seemed to be formed at a lower temperature and then tran-formed to the layered perovskite phase as the heating temperature increased. In the thin films pyrolyzed at formed to the layered perovskte phase as the heating temperature increased. In the films pyrolyzed at $750^{\circ}C$ the amount of $Bi_4Ti_3O_{12}{\cdot}BaTiO_3$ reached to 94% while $Bi_4Ti_3O_{12}{\cdot}BaTiO_3$ was 77% in composition. This result shows that the formation of the layered pervoskite phase becomes difficult as the amount of complexing $BaTiO_3$ increases. The microstructures and the electrical properties of the thin films were gen-erally improved with the incease of the heating temperature. However the presence of the pyrochlore phase could not be removed effectively. Our study showed that the electrical properties of $Bi_4Ti_3O_{12}{\cdot}BaTiO_3$ were pronouncedly improved with complexing with BaTiO3 when compared to those of $Bi_4Ti_3O_{12}$ while the presence of the pyrochlore phase was detrimental to the those of $Bi_4Ti_3O_{12}{\cdot}2BaTiO_3$.

• Environmental Engineering Research
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• v.18 no.1
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• pp.21-28
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• 2013

In this study, the applicability of visible light-emitting-diodes (LEDs) to the photocatalytic degradation of indoor-level trichloroethylene (TCE) and perchloroethylene (PCE) over N-doped $TiO_2$ (N-$TiO_2$) was examined under a range of operational conditions. The N-$TiO_2$ photocatalyst was calcined at $650^{\circ}C$ (labeled N-650) showed the lowest degradation efficiencies for TCE and PCE, while the N-$TiO_2$ photocatalysts calcined at $350^{\circ}C$, $450^{\circ}C$, and $550^{\circ}C$ (labeled as N-350, N-450, and N-550, respectively) exhibited similar or slightly different degradation efficiencies to those of TCE and PCE. These results were supported by the X-ray diffraction patterns of N-350, N-450, N-550, and N-650. The respective average degradation efficiencies for TCE and PCE were 96% and 77% for the 8-W lamp/N-$TiO_2$ system, 32% and 20% for the violet LED/N-$TiO_2$ system, and ~0% and 4% for the blue LED/N-$TiO_2$ system. However, the normalized photocatalytic degradation efficiencies for TCE and PCE for the violet LED-irradiated N-$TiO_2$ system were higher than those from the 8-W fluorescent daylight lamp-irradiated N-$TiO_2$ system. Although the difference was not substantial, the degradation efficiencies exhibited a decreasing trend with increasing input concentrations. The degradation efficiencies for TCE and PCE decreased with increasing air flow rates. In general, the degradation efficiencies for both target compounds decreased as relative humidity increased. Consequently, it was indicated that violet LEDs can be utilized as energy-efficient light sources for the photocatalytic degradation of TCE and PCE, if operational conditions of N-$TiO_2$ photocatalytic system are optimized.

• Journal of the Korean Society for Heat Treatment
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• v.3 no.1
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• pp.1-7
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• 1990

To investigate the influence of r.f. power and electrode distance on the TiN deposition, TiN films were deposited onto STC3, STD11 steel and Si-wafer from gas mixtures of $TiC_4/N_2/H_2$ using the radio frequency plasma assisted chemical vapor deposition. The crystallinity of TiN film could be improved by the increase of r.f. power and the decrease of electrode distance. The TiN coated layer contains chlorine, its content were decreased with increasing r.f. power as well as decreasing electrode distance. And the thickness of deposited TiN was largely affected by r.f. power and electrode distance. The hardness of deposited TiN reached a maximum value of about Hv 2,000.

• Journal of the Korean institute of surface engineering
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• v.38 no.6
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• pp.207-211
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• 2005

In this work a multi-layered nanostructured TiAIN/CrN superlattice coatings was synthesized using closed-field unbalanced magnetron sputtering method and the relationships between their superlattice period (1), micro-structure, hardness and elastic modulus were investigated. In addition, wear test at $500^{\circ}C$ and oxidation resistance test at $900^{\circ}C$ were performed to investigate high temperature properties of these thin films. The coatings were characterized in terms of microstructure and mechanical properties by transmission electron microscopy (TEM) and nano-indentation test. Results from TEM analysis showed that superlattice periods was inversely proportional to the jig rotation speed. The maximum hardness and elastic modulus of 37 GPa and 375 GPa were observed at superalttice period of 6.1 nm and 4.4 nm, respectively. An higher value of microhardness from TiAIN/CrN thin films than either TiAIN (30 GPa) or CrN (26 GPa) was noted while the elastic modulus was approximately an average of TiAIN and CrN films. These enhancement effects in superlattice films could be attributed to the resistance to dislocation glide across interface between the CrN and TiAIN layers. Much improved plastic deformation resistance ($H^3/E^2$) of 0.36 from TiAIN/CrN coatings was observed, compared with 0.15 and 0.16 from TiAIN and CrN, respectively. Also the wear resistance at $500^{\circ}C$ was largely increased than those of single TiAIN and CrN coatings and TiAIN/CrN coatings showed much reduced weight gain after exposure at $900^{\circ}C$ for 20 hours.