• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1514-1516
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• 1999

This paper covers our efforts to improve the low carrier mobility and light instability of hydrogenated amorphous silicon (a-Si:H) films with microcrystalline silicon $({\mu}c-Si)$ films. We successfully prepared ${\mu}c-Si$ films on $CaF_2$/glass substrate by decomposition of $SiH_4$ in RPCVD system. The $CaF_2$ films on glass served as a seed layer for ${\mu}c-Si$ film growth. The XRD analysis on $CaF_2$/glass illustrated a (111) preferred $CaF_2$ grains with the lattice mismatch less than 5 % of Si. We achieved ${\mu}c-Si$ films with a crystalline volume fraction of 61 %, (111) and (220) crystal orientations. grain size of $706\AA$, activation energy of 0.49 eV, and Photo/dark conductivity ratio of 124. By using a $CaF_2$/glass structure. we were able to achieve an improved ${\mu}c-Si$ films at a low substrate temperature of $300^{\circ}C$.

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.503-509
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• 2001

Thin films of hydrogenated amorphous silicon (a-Si : H) and hydrogenated amorphous silicon carbide (a-SiC:H) of different compositions were deposited on Si(100) wafer and glass by RF plasma-enhanced chemical vapor deposition (RF-PECVD). In the present work, we have investigated the effects of the RF power on the properties, such as optical band gap, transmittance and crystallinity. The Raman data show that the a-Si:H material consists of an amorphous and crystalline phase for the co-presence of two peaks centered at 480 and $520 cm^{-1}$ . The UV-VIS data suggested that the optical energy band gap ($E_{g}$ ) is not changed effectively with RF power and the obtained $E_{g}$(1.80eV) of the $\mu$c-Si:H thin film has almost the same value of a-Si:H thin film (1.75eV), indicating that the crystallity of hydrogenated amorphous silicon thin film can mainly not affected to their optical properties. However, the experimental results have shown that$ E_{g}$ of the a-SiC:H thin films changed little on the annealing temperature while $E_{g}$ increased with the RF power. The Raman spectrum of the a-SiC:H thin films annealed at high temperatures showed that graphitization of carbon clusters and microcrystalline silicon occurs.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.181-181
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• 2016

Hydrogenated microcrystalline silicon (${\mu}c-Si:H$) films have attracted much attention as materials of the bottom-cells in Si thin film tandem photovoltaics due to their low bandgap and excellent stability against light soaking. However, in PECVD, the source gas $SiH_4$ must be highly diluted by $H_2$, which eventually results in low deposition rate. Moreover, it is known that high-rate ${\mu}c-Si:H$ growth is usually accompanied by a large number of dangling-bond (DB) defects in the resulting films, which act as recombination centers for photoexcited carriers, leading to a deterioration in the device performance. During film deposition, Si nanoparticles generated in $SiH_4$ discharges can be incorporated into films, and such incorporation may have effects on film properties depending on the size, structure, and volume fraction of nanoparticles incorporated into films. Here we report experimental results on the effects of nonoparticles incorporation at the different substrate temperature studied using a multi-hollow discharge plasma CVD method in which such incorporation can be significantly suppressed in upstream region by setting the gas flow velocity high enough to drive nanoparticles toward the downstream region. All experiments were performed with the multi-hollow discharge plasma CVD reactor at RT, 100, and $250^{\circ}C$, respectively. The gas flow rate ratio of $SiH_4$ to $H_2$ was 0.997. The total gas pressure P was kept at 2 Torr. The discharge frequency and power were 60 MHz, 180 W, respectively. Crystallinity Xc of resulting films was evaluated using Raman spectra. The defect densities of the films were measured with electron spin resonance (ESR). The defect density of fims deposited in the downstream region (with nonoparticles) is higher defect density than that in the upstream region (without nanoparticles) at low substrate temperature of RT and $100^{\circ}C$. This result indicates that nanoparticle incorporation can change considerably their film properties depending on the substrate temperature.

• The Korean Journal of Ceramics
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• v.4 no.3
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• pp.199-203
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• 1998

$Pb(Zr, Ti)O_3$ (Pb:Zr:Ti=1:0.52:0.48) thin films were prepared on single crystal MgO(100) substrates by dipping-pyrolysis process using a solution of constituent metal naphthenates as starting materials. The solution was spin-coated onto substrate and the precursor films were pyrolyzed at $200^{\circ}C$ in air or at $200^{\circ}C$ in argon for 1, 2, 5 and 24h, followed by final heat treatment at $750^{\circ}C$. For all the films, highly (h00)/(00l)-oriented Pb$Pb(Zr, Ti)O_3$ thin films with smooth surfaces and crack-free were obtained, whereas thin film pyrolyzed in air for 24 h exhibited polycrystalline character. According to the pole-figure analysis, epitaxy of the product films was found to depend on pyrolysis atmosphere.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1999.06a
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• pp.285-303
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• 1999

Thin films of hydrogenated amorphous silicon carbide compounds (a-SixC1x:H) of different compositions were deposited on Si substrate by RF plasma-enhanced chemical vapor deposition (PECVD). Experiments were carried out using silane(SiH4) and methane(CH4) as the gas precursors at 1 Torr and at low substrate temperature (25$0^{\circ}C$). The gas flow rate was changed with every other parameters (pressure, temperature, RF power) fixed. The substrate was Si(100) wafer and all of the films obtained were amorphous. The bonding structure of a-SixC1x:H films deposited was investigated by X-ray photoelectron spectroscopy (XPS) for the film compositions. In addition, the surface morphology of films was investigated by atomic force microscopy (AFM).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.165-165
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• 2010

AZO:H films were prepared by RF magnetron sputtering system with a AZO (2wt% $Al_2O_3$) ceramic target at a temperature of $150^{\circ}C$. The annealing treatments were carried out in hydrogen ambient for 1hr at a temperature of $400^{\circ}C$. The AZO:H films were etched with 1 % HCl. The influence of the properties of AZO:H films deposited in various working pressures is investigated. As a result, the AZO:H film deposited in 4mTorr showed excellent electrical property of $\rho=5.036{\times}10^{-4}{\Omega}cm$ and strongly oriented (002) peak. The transmittance in the wavelength of 450nm was above 80%. It can be used as front electrode for increasing efficiency of GaN LED.

• Journal of Korean Vacuum Science & Technology
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• v.4 no.3
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• pp.86-90
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• 2000

ZnO : Al films were prepared through the optimization process of aluminum content and substrate temperature in rf-magnetron sputtering. When hydrogenation was performed on these films using a hot filament method, all films showed improvement in conductivity although more conductive film showed less improvement. When the substrate temperature ($T_H$) was varied from $25^{\circ}C\;to\;300^{\circ}C$ during hydrogenation, the resistivity was reduced more at higher $T_H$ (more than 30% at $T_H=300^{\circ}C$) Thus, two methods were developed to suppress the dehydrogenation in ZnO : Al films : (1) capping with amorphous silicon thin film as a diffusion barrier, and (2) cooling during hydrogenation.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.06a
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• pp.72-72
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• 2001

Plasma polymerized thin films have been deposited on Si(lOO) substrates at $25-400^{\circ}C$ using thiophene ($C_4H_4S$) precursor by plasma assisted chemical vapor deposition (PACVD) method for low-dielectric device application. In order to compare physical properties of the as-grown thin films, the effects of the plasma power, gas flow ratio and deposition temperature on the dielectric constant and thermal stability were mainly studied. XRD and TED studies revealed that the as-grown thin films have highly oriented amorphous polymer structure. XPS data showed that the polymerized thin films that grown under different RF power and deposition temperature as well as different gas ratio of $Ar:H_2$ have different stoichiometric ratio of C and S compared with that of monomer, indicating a formation of mixture polymers. Moreover, we also realized that oxygen free and thermally stable polymer thin films could be grown at even $400^{\circ}C$. The results of SEM, AFM and TEM showed that the polymer films with smooth surface and sharp interface could be grown under various deposition conditions. From the electrical property measurements such as I-V and C-V characteristics, the minimum dielectric constant and the best leakage current were obtained to be about 3.22 and $10-11{\;}A/\textrm{cm}^2$, respectively.

• Journal of the Korean Vacuum Society
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• v.7 no.4
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• pp.368-373
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• 1998

As device dimensions approach submicrometer size in ULSI, the demand for interlayer dielectric materials with very low dielectric constant is increased to solve problems of RC delay caused by increase in parasitic resistance and capacitance in multilevel interconnectins. Fluorinated amorphous carbon in one of the promising materials in ULSI for the interlayer dielectric films with low dielectric constant. However, poor thermal stability and adhesion with Si substrates have inhibited its use. Recently, amorphous hydrogenated carbon (a-C:H) film as a buffer layer between the Si substrate and a-C:F has been introduced because it improves the adhesion with Si substrate. In this study, therfore, a-C:F/a-C:H films were deposited on p-type Si(100) by ECRCVD from $C_2F_6, CH_4$and $H_2$gas source and investigated the effect of forward power and composition on the thickness, chemical bonding state, dielectric constant, surface morphology and roughness of a-C:F films as an interlayer dielectric for ULSI. SEM, FT-IR, XPS, C-V meter and AFM were used for determination of each properties. The dielectric constant in the a-C:F/a-C:H films were found to decrease with increasing fluorine content. However, the dielectric constant increased after furnace annealing in $N_2$atomosphere at $400^{\circ}C$ for 1hour due to decreasing of flurorine content. However, the dielectric constant increased after furnace annealing in $N_2$atmosphere at $400^{\circ}C$ for 1hour due to decreasing of fluorine concentration.

• Progress in Superconductivity and Cryogenics
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• v.19 no.3
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• pp.13-17
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• 2017

We investigated the effect of self-assembled BSO nano-defects as pinning centers in BSO-added GdBCO films when the thicknesses of films were varied. 3.5 vol. % BSO-added GdBCO films with varying thicknesses from 200 nm to 1000 nm were deposited on $SrTiO_3$ (STO) substrate by using pulsed laser deposition (PLD) process. For the films with thicknesses of 400 nm and 600 nm, 'anomaly shoulders' in $J_c-H$ characteristic curves were observed near the matching field. The anomaly shoulders appeared in the field dependence of $J_c$ may be attributed to the existence of double pinning mechanisms in thin films. The fit to the pinning force density as a function of reduced field h ($H/H_{irr}$) using the Dew-Hughes' scaling law shows that both the 400 nm- and the 600 nm-thick films have double pinning mechanisms while the other films have a single pinning mechanism. These results indicate that the self-assembled property of BSO result in different role as pinning centers with different thickness.