• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.7 no.3
• /
• pp.468-473
• /
• 2003

In this paper, for enhancement of property on a-Si:H TFTs We measure interface characteristics of ferroelectrics thin film and a-Si:H thin film. First, SrTiO$_3$ thin film is deposited bye-beam evaporation. Deposited films are annealed for 1 hour in N2 ambient at $150^{\circ}C∼600^{\circ}C$. Dielectric characteristics of deposited SrTiO$_3$ films are very good because dielectric constant shows 50∼100 and breakdown electric field are 1 ∼ 1.5 MV/cm. a-SiN:H,a-Si:H(n-type a-Si:H) are deposited onto SrTiO$_3$ film to make MFNS(Meta1/ferroelectric/a-SiN:H/a-Si:H) by PECVD. After the C-V measurement for interface characteristics, MFNS structure shows no difference with MNS(Metal/a-SiN:H/a-Si:H) structure in C-V characteristics but the insulator capacitance value of MFNS structure is much higher than the MNS because of high dielectric constant of ferroelectric.

• Journal of IKEEE
• /
• v.18 no.4
• /
• pp.620-624
• /
• 2014

In this study, the electrical characteristics of Ni/CNT/$SiO_2$ structures were investigated in order to analyze the mechanism of carbon nanotubes in 4H-SiC MIS device structures. We fabricated 4H-SiC MIS capacitors with or without carbon nanotubes. Carbon nanotubes were dispersed by isopropyl alcohol. The capacitance-voltage (C-V) is characterized at 300 to 500K. The experimental flat-band voltage ($V_{FB}$) shift was positive. Near-interface trapped charge density and oxide trapped charge density values of Ni/CNT/$SiO_2$ structure were less than values of reference samples. With increasing temperature, the flat-band voltage was negative. It has been found that its oxide quality is related to charge carriers or defect states in the interface of 4H-SiC MIS capacitors. Gate characteristics of 4H-SiC MIS capacitors can be controlled by carbon nanotubes between Ni and $SiO_2$.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.7 no.3
• /
• pp.393-399
• /
• 1997

H-SiC single crystals were successfully grown by the sublimation method and the optimum growth conditions were established. The grown SiC crystals were about 33 mm in diameter and 11 mm in length. The micropipe density of the polished SiC wafers was 400/$\textrm{cm}^2$, and the planar defect density was 50/$\textrm{cm}^2$. Raman spectroscopy and DCXRD analysis were used to examine the crystallinity of Acheson seeds and the 6H-SiC wafers. As a result, the crystallinity of the 6H-SiC wafers was better than that of Acheson seeds. For examination of the electrical properties of the undopped 6H-SiC wafers Hall measurements were applied. According to the measurements the carrier concentration was estimated to be $3.91{\times}10^{15}/\textrm {cm}^3$ and doping type of the undopped. 6H-SiC wafers was n-type.

• Korean Journal of Materials Research
• /
• v.9 no.10
• /
• pp.1006-1011
• /
• 1999

B-doped hydrogenated amorphous silicon carbide (a-SiC:H) thin films were prepared by plasma-enhanced chemical-vapor deposition in a gas mixture of $SiH_4$, $CH_4$ and $B_2H_6$. Microstructures and chemical properties of a-SiC:H films grown with varing the volume ratio of $CH_4$ to $SiH_4$ were characterized with various analysis methods including scanning electron microscopy(SEM), X-ray diffractometry(XRD), Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy. X-ray photoelectron spectroscopy(XPS), UV absorption spectroscopy and photoconductivity measurements. While Si:H films grown without $CH_4$ showed amorphous state, the addition of $CH_4$ during deposition enhanced the development of a microcrystalline phase. By introducing C atoms into the film, Si-Si and Si--$\textrm{H}_{n}$ bonds of a -Si:H films were gradually replaced by Si-C, C-C, and Si--$\textrm{C}_{n}\textrm{H}_{m}$ bonds. Consequently, the electrical resistivity and optical bandgap of a-SiC:H films were increased with the C concentration in the film.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2003.05a
• /
• pp.501-504
• /
• 2003

In this paper, for enhancement of property on a-Si:H TFTs We measure interface characteristics of ferroelectrics thin film and a-Si:H thin film. First, SrTiO$_3$ thin film is deposited bye-beam evaporation. Deposited films are annealed for 1 hour in N2 ambient at 150$^{\circ}C$ ∼ 600$^{\circ}C$. Dielectric characteristics of deposited SrTiO$_3$ films are very good because dielectric constant shows 50∼100 and breakdown electric field are 1∼1.5MV/cm. a-SiN:H,a-Si:H(n-type a-Si:H) are deposited onto SrTiO$_3$ film to make MFNS(Metal/ferroelectric/a-SiN:H/a-Si:H) by PECVD. After the C-V measurement for interface characteristics, MFNS structure shows no difference with MNS(Metal/a-SiN:H/a-Si:H) structure in C-V characteristics but the insulator capacitance value of MFNS structure is much higher than the MNS because of high dielectric constant of ferroelectrics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.6
• /
• pp.441-445
• /
• 2013

ZnO nanowires on the a-, c- and m-plane oriented 4H-SiC substrates were grown by using a high temperature tube furnace. Ti/Au electrodes were deposited on ZnO nanowires and a-, c- and m-plane 4H-SiC substrates, respectively. The shape and density of the ZnO nanowires were investigated by field emission scanning electron microscope. It was found that the growth direction of nanowires depends strongly on growth parameters such as growth temperature and pressure. In this work, The sensitivity of nanowires formed a-, c- and m-plane oriented 4H-SiC gas sensor was measured at $300^{\circ}C$ with CO gas concentration of 80%. The nanowires grown on a-plane oriented 4H-SiC show improved sensing performance than those on c- and m-plane oriented 4H-SiC due to the increased density of nanowire on a-plane 4H-SiC.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.33 no.2
• /
• pp.45-53
• /
• 2023

The growth of Si on 4H-SiC substrate has a wide range of applications as a very useful material in power semiconductors, bipolar junction transistors and optoelectronics. However, it is considerably difficult to grow very fine crystalline Si on 4H-SiC owing to the lattice mismatch of approximately 20 % between Si and 4H-SiC. In this paper, we report the growth of a Si epilayer by an Al-related nanostructure cluster grown on a 4H-SiC substrate using a mixed-source hydride vapor phase epitaxy (HVPE) method. In order to grow hexagonal Si on the 4H-SIC substrate, we observed the process in which an Al-related nanostructure cluster was first formed and an epitaxial layer was formed by absorbing Si atoms. From the FE-SEM and Raman spectrum results of the Al-related nanostructure cluster and the hexagonal Si epitaxial layer, it was considered that the hexagonal Si epitaxial layer had different characteristics from the general cubic Si structure.

• Journal of the Korean Ceramic Society
• /
• v.35 no.12
• /
• pp.1336-1336
• /
• 1998

A twt -step carbothermal reduction scheme has been employed for the synthesis of SiC whiskers in an Ar or a H2 atmosphere via vapor-solid two-stage and vapor-liquid-solid growth mechanism respectively. It has been shown that the whisker growth proceed through the following reaction mechanism in an Ar at-mosphere : SiO2(S)+C(s)-SiO(v)+CO(v) SiO(v)3CO(v)=SiC(s)whisker+2CO2(v) 2C(s)+2CO2(v)=4CO(v) the third reaction appears to be the rate-controlling reaction since the overall reaction rates are dominated by the carbon which is participated in this reaction. The whisker growth proceeded through the following reaction mechaism in a H2 atmosphere : SiO2(s)+C(s)=SiO(v)+CO(v) 2C(s)+4H2(v)=2CH4(v) SiO(v)+2CH4(v)=SiC(s)whisker+CO(v)+4H2(v) The first reaction appears to be the rate-controlling reaction since the overall reaction rates are enhanced byincreasing the SiO vapor generation rate.

• Journal of the Korean Ceramic Society
• /
• v.32 no.6
• /
• pp.685-696
• /
• 1995

The most important techniques in the synthesis of SiC/C function gradient material (FGM) are to control the SiC/C ratio and to obtain the moderate deposition rate. For these, various gas systems and flow rates were attempted and evaluated. It turned out that the CH4＋SiCl4＋H2 system was suitable for the deposition of SiC-rich layers, the C3H8＋SiCl4＋Ar system for the deposition of carbon-rich layers, and the C3H8＋SiCl4＋H2＋Ar system was good to deposit the layers between them.

• The Korean Journal of Ceramics
• /
• v.5 no.3
• /
• pp.224-229
• /
• 1999

The preparation and toughening of SiC-AIN solid solution from powder mixtures of $\beta$-SiC, AIN and $\alpha$-SiC by hot-pressing were studied in the 1870 to $2030^{\circ}C$ temperature range. The reaction of AIN and $\beta$-SiC(3C) powders causing transformation to the 2H(wurtzite) structure appeared to depend on hot-pressing temperatures and an additive of $\alpha$-SiC. For the composition of 49wt% SiC with 2 wt% $\alpha$-SiC and 47.5 wt% AIN47.5wt% SiC with 5 wt % $\alpha$-SiC at 203$0^{\circ}C$ for 1 h, th complete solid solutions with a single phase of 2H could be obtained. The appreciable amount of $\alpha$-SiC could develop the columnar inter-grains of 4H phase and the stable 2H phase with the relatively uniform composition and grain size distributions. The effect of $\alpha$-SiC on the phases present and compositional microstructures with columnar inter-grains was invetigated using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The fracture toughness and Vickers hardness of the hot-pressed solid solutions wre examined by the indentation-fracture-test method.