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The Effect of TiO2 Addition on Low-temperature Sintering Behaviors in a SnO2-CoO-CuO System
이재상,오경식,백용균 한국분말재료학회 2024 한국분말재료학회지 (KPMI) Vol.31 No.2
Pure SnO2 has proven very difficult to densify. This poor densification can be useful for the fabrication of SnO2 with a porous microstructure, which is used in electronic devices such as gas sensors. Most electronic devices based on SnO2 have a porous microstructure, with a porosity of > 40%. In pure SnO2, a high sintering temperature of approximately 1300C is required to obtain > 40% porosity. In an attempt to reduce the required sintering temperature, the present study investigated the low-temperature sinterability of a current system. With the addition of TiO2, the compositions of the samples were Sn1-xTixO2-CoO(0.3wt%)-CuO(2wt%) in the range of x ≤ 0.04. Compared to the samples without added TiO2, densification was shown to be improved when the samples were sintered at 950C. The dominant mass transport mechanism appears to be grain-boundary diffusion during heat treatment at 950C.
Crystalline and Electrical Properties of BST/4H-SiC Capacitors
이재상,조영덕,고중혁,하재근,구상모 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.61
We report on the application of high-k dielectric Ba0.5Sr0.5TiO3 (BST) thin films for metalinsulator-semiconductor (MIS) structures on 4H-SiC. The temperature-dependent electrical properties were measured at temperatures up to 250 ℃ and the effect of post-annealing on the structural and the electrical properties of structures were examined by using X-ray diffraction (XRD),atomic force microscopy (AFM) and capacitance-voltage (C-V) measurements. The BST films postannealed at 850 ℃ for 1 hour exhibited enhanced crystalline properties with orientations including the [110] and the [100] directions, increased dielectric constants (~360 at room temperature), and increased average grain sizes (~200 nm) and roughness values (~11.5nm). Stable characterizations of the Ag/BST/4H-SiC capacitors were made at elevated temperatures up to 250 ℃, which demonstrate that the BST/SiC structure is a promising device element for high-temperature applications.
이온주입 공정을 이용한 4H-SiC p-n Diode에 관한 시뮬레이션 연구
이재상,방욱,김상철,김남균,구상모,Lee, Jae-Sang,Bahng, Wook,Kim, Sang-Cheol,Kim, Nam-Kyun,Koo, Sang-Mo 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.2
Silicon carbide (SiC) has attracted significant attention for high frequency, high temperature and high power devices due to its superior properties such as the large band gap, high breakdown electric field, high saturation velocity and high thermal conductivity. We performed Al ion implantation processes on n-type 4H-SiC substrate using a SILVACO ATHENA numerical simulator. The ion implantation model used Monte-Carlo method. We simulated the effect of channeling by Al implantation in both 0 off-axis and 8 off-axis n-type 4H-SiC substrate. We have investigated the effect of varying the implantation energies and the corresponding doses on the distribution of Al in 4H-SiC. The controlled implantation energies were 40, 60, 80, 100 and 120 keV and the implantation doses varied from $2{\times}10^{14}$ to $1{\times}10^{15}\;cm^{-2}$. The Al ion distribution was deeper with increasing implantation energy, whereas the doping level increased with increasing dose. The effect of post-implantation annealing on the electrical properties of Al-implanted p-n junction diode were also investigated.