• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.278-280
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• 2007

a-Si:H/${\mu}$c-Si:H 적층형 태양전지의 효율향상을 위해 상부전지와 하부전지간의 접합특성은 매우 중요하다. 본 연구에서는, 접합특성을 향상하기 위하여 아몰퍼스 보다 전도도가 높은 마이크로화된 n층 또는 ZnO:Al을 중간층으로 삽입한 태양전지를 제조하였으며, 그 특성을 전기적, 광학적 방법으로 분석하였다. 전기적 특성에서, 상부전지 n층에 아몰퍼스를 적용한 태양전지의 경우, 상부전지와 하부전지 간의 직렬저항이 $500{\Omega}-cm^2$ 이상으로 높게 측정되었고, 이에 따라 AM 1.5 상태의 I-V 특성에서 비틀림 현상이 발생하여 곡선인자(Fill Factor : FF)가 낮게 측정되었다. 이에 반하여, 상부전지 n층에 마이크로층을 적용하거나, ZnO:Al 중간층을 삽입한 시편의 경우, 상부전지와 하부전지간의 직렬저항이 $1{\Omega}-cm^2$ 이하로 감소하였으며, 이와 같은 계면간의 접합특성 향상으로 I-V특성에서 비틀림 현상이 사라지고, FF가 70% 까지 증가하였다. 또한, 마이크로층과 ZnO:Al 중간층을 동시에 적용한 태양전지의 경우, FF가 75%까지 가장 높게 증가하였다. 광학적 특성의 경우, 같은 두께의 아몰퍼스 n층에 비하여 마이크로 n층이 투과도는 더 높게, 반사도는 낮게 측정되었으며, 이는 하부전지의 단락전류 (Short circuit current : Jsc)를 높여줄 것으로 판단된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.78-78
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• 2012

In this presentation I will review the expanding thermal plasma chemical vapour deposition (ETP-CVD) technology, a deposition technology capable of reaching ultrahigh deposition rates. High rate deposition of a-Si:H, ${\mu}c$-Si:H, a-SiNx:H and silicon nanocrystals will be discussed and their various applications, mainly for photovoltaic applications demonstrated. An important aspect over the years has been the fundamental investigation of the growth mechanism of these films. The various in situ (plasma) and thin film diagnostics, such as Langmuir probes, retarding field analyzer, (appearance potential) mass spectrometry and cavity ring absorption spectroscopy, spectroscopic ellipsometry to name a few, which were successfully applied to measure radical and ion density, their temperature and kinetic energy and their reactivity with the growth surface. The insights gained in the growth mechanism provided routes to novel applications of the ETP-CVD technology, such as the ultrahigh high growth rate of silicon nanorystals and surface passivation of c-Si surfaces.

• Journal of the Korean Magnetics Society
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• v.17 no.3
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• pp.120-123
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• 2007

The typical double-barrier magnetic tunnel junction (DMTJ) structure examined in this paper consists of a Ta 45/Ru 9.5/IrMn 10/CoFe7/$AlO_x$/free layer/AlO/CoFe 7/IrMn 10/Ru 60 (nm). The free layer consists of an $Ni_{16}Fe_{62}Si_8B_{14}$ 7 nm, $Co_{90}Fe_{10}$ (fcc) 7 nm, or CoFe $t_1$/NiFeSiB $t_2$/CoFe $t_1$ layer in which the thicknesses $t_1$ and $t_2$ are varied. The DMTJ with an NiFeSiB-free layer had a tunneling magnetoresistance (TMR) of 28%, an area-resistance product (RA) of $86\;k{\Omega}{\mu}m^2$, a coercivity ($H_c$) of 11 Oe, and an interlayer coupling field ($H_i$) of 20 Oe. To improve the TMR ratio and RA, a DMTJ comprising an amorphous NiFeSiB layer that could partially substitute for the CoFe free layer was investigated. This hybrid DMTJ had a TMR of 30%, an RA of $68\;k{\Omega}{\mu}m^2$, and a of 11 Oe, but an increased of 37 Oe. We confirmed by atomic force microscopy and transmission electron microscopy that increased as the thickness of NiFeSiB decreased. When the amorphous NiFeSiB layer was thick, it was effective in retarding the columnar growth which usually induces a wavy interface. However, if the NiFeSiB layer was thin, the roughness was increased and became large because of the magnetostatic $N{\acute{e}}el$ coupling.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.77-77
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• 1998

Present silicon dioxide (SiOz) 떠m as intennetal dielectridIMD) layers will result in high parasitic c capacitance and crosstalk interference in 비gh density devices. Low dielectric materials such as f f1uorina뼈 silicon oxide(SiOF) and f1uoropolymer IMD layers have been tried to s이ve this problem. I In the SiOF ftlm, as fluorine concentration increases the dielectric constant of t뼈 film decreases but i it becomes unstable and wa않r absorptivity increases. The dielectric constant above 3.0 is obtain어 i in these ftlms. Fluoropolymers such as polyte$\sigma$따luoroethylene(PTFE) are known as low dielectric c constant (>2.0) materials. However, their $\alpha$)Or thermal stability and low adhesive fa$\pi$e have h hindered 야1리ru뚱 as IMD ma따"ials. 1 The concept of a plasma processing a찌Jaratus with 비gh density plasma at low pressure has r received much attention for deposition because films made in these plasma reactors have many a advantages such as go여 film quality and gap filling profile. High ion flux with low ion energy in m the high density plasma make the low contamination and go어 $\sigma$'Oss피lked ftlm. Especially the h helicon plasma reactor have attractive features for ftlm deposition 야~au똥 of i앙 high density plasma p production compared with other conventional type plasma soun:es. I In this pa야Jr, we present the results on the low dielectric constant fluorocarbonated-SiOF film d밑JOsited on p-Si(loo) 5 inch silicon substrates with 00% of 0dFTES gas mixture and 20% of Ar g gas in a helicon plasma reactor. High density 띠asma is generated in the conventional helicon p plasma soun:e with Nagoya type ill antenna, 5-15 MHz and 1 kW RF power, 700 Gauss of m magnetic field, and 1.5 mTorr of pressure. The electron density and temperature of the 0dFTES d discharge are measUI벼 by Langmuir probe. The relative density of radicals are measured by optic허 e emission spe따'Oscopy(OES). Chemical bonding structure 3I피 atomic concentration 따'C characterized u using fourier transform infrared(FTIR) s야3띠"Oscopy and X -ray photonelectron spl:’따'Oscopy (XPS). D Dielectric constant is measured using a metal insulator semiconductor (MIS;AVO.4 $\mu$ m thick f fIlmlp-SD s$\sigma$ucture. A chemical stoichiome$\sigma$y of 야Ie fluorocarbina$textsc{k}$영-SiOF film 따~si야영 at room temperature, which t the flow rate of Oz and FTES gas is Isccm and 6sccm, res야~tvely, is form려 야Ie SiouFo.36Co.14. A d dielec$\sigma$ic constant of this fIlm is 2.8, but the s$\alpha$'!Cimen at annealed 5OOt: is obtain려 3.24, and the s stepcoverage in the 0.4 $\mu$ m and 0.5 $\mu$ m pattern 킹'C above 92% and 91% without void, res야~tively. res야~tively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.6
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• pp.256-259
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• 2006

The amorphous $SiO_x$ nanowires were synthesized by the vapor phase epitaxy (VPE) method. $SiO_x$ nanowires were formed on silicon wafer of temperatures ranged from $800{\sim}1100^{\circ}C$ and nickel thin film was used as a catalyst for the growth of nanowires. A vapor-liquid-solid (VLS) mechanism is responsible for the catalyst-assisted amorphous $SiO_x$ nanowires synthesis in this experiment. The SEM images showed cotton-like nanostructure of free standing $SiO_x$ nanowires with the length of more than about $10{\mu}m$. The $SiO_x$ nanowires were confirmed amorphous structure by TEM analysis and EDX spectrum reveals that the nanowires consist of Si and O.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.204-205
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• 2011

In thin film silicon solar cells, p-i-n structure is adopted instead of p/n junction structure as in wafer-based Si solar cells. PECVD is a most widely used thin film deposition process for a-Si:H or ${\mu}c$-Si:H solar cells. For best performance of thin film silicon solar cell, the dopant profiles at p/i and i/n interfaces need to be as sharp as possible. The sharpness of dopant profiles can easily achieved when using multi-chamber PECVD equipment, in which each layer is deposited in separate chamber. However, in a single-chamber PECVD system, doped and intrinsic layers are deposited in one plasma chamber, which inevitably impedes sharp dopant profiles at the interfaces due to the contamination from previous deposition process. The cross-contamination between layers is a serious drawback of a single-chamber PECVD system in spite of the advantage of lower initial investment cost for the equipment. In order to resolve the cross-contamination problem in single-chamber PECVD systems, flushing method of the chamber with NH3 gas or water vapor after doped layer deposition process has been used. In this study, a new plasma process to solve the cross-contamination problem in a single-chamber PECVD system was suggested. A single-chamber VHF-PECVD system was used for superstrate type p-i-n a-Si:H solar cell manufacturing on Asahi-type U FTO glass. A 80 MHz and 20 watts of pulsed RF power was applied to the parallel plate RF cathode at the frequency of 10 kHz and 80% duty ratio. A mixture gas of Ar, H2 and SiH4 was used for i-layer deposition and the deposition pressure was 0.4 Torr. For p and n layer deposition, B2H6 and PH3 was used as doping gas, respectively. The deposition temperature was $250^{\circ}C$ and the total p-i-n layer thickness was about $3500{\AA}$. In order to remove the deposited B inside of the vacuum chamber during p-layer deposition, a high pulsed RF power of about 80 W was applied right after p-layer deposition without SiH4 gas, which is followed by i-layer and n-layer deposition. Finally, Ag was deposited as top electrode. The best initial solar cell efficiency of 9.5 % for test cell area of 0.2 $cm^2$ could be achieved by applying the in-situ plasma cleaning method. The dependence on RF power and treatment time was investigated along with the SIMS analysis of the p-i interface for boron profiles.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.1
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• pp.63-70
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• 1994

Single crystals of the superionic conductor ${\beta}-Ag_3SI$ were prepared by thermal treatmentr from the reactant mixture of AgI and $Ag_2S$. The growing single crystals were made to spherical shape of $200{mu}m$ in diameter. The detailed structures analyses revealed that $Ag^+$ in ${\beta}-Ag_3SI$ distribute on 12h site of 4-coordination inpreference to 3c site of 6-coordination. The effective one-particle potential (o.p.p.). of $Ag^+$ along [110] direction was evaluated from the probability density function(p.d.f.) Activation energy calculated from the o.p.p. curve has been found to be 0.012 eV for the diffusion of $Ag^+$ on (001) plane in the ${\beta}-Ag_3SI$ structure.

• Journal of Electrical Engineering and information Science
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• v.2 no.5
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• pp.65-71
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• 1997

We present heterojunction solar cells with a structure of metal/a-Si:H(n-i-p)/poly-Si(n-p)/metal for the terrestrial applications. This cell consists fo two component cells: a top n-i-p junction a-Si:Hi cell with wide-bandgap 1.8eV and a bottom n-p junction poly-Si cell with narrow-bandgap 1.1eV. The efficiency influencing factors of the solar cell were investigated in terms of simulation an experiment. Three main topics of the investigated study were the bottom cell with n-p junction poly-Si, the top a-Si:H cell with n-i-p junction, and the interface layer effects of heterojunction cell. The efficiency of bottom cell was improved with a pretreatment temperature of 900$^{\circ}C$, surface polishing, emitter thickness of 0.43$\mu\textrm{m}$, top Yb metal, and grid finger shading of 7% coverage. The process optimized cell showed a conversion efficiency about 16%. Top cell was grown by suing a photo-CVD system which gave an ion damage free and good p/i-a-Si:H layer interface. The heterojunction interface effect was examined with three different surface states; a chemical passivation, thermal oxide passivation, and Yb metal. the oxide passivated cell exhibited the higher photocurrent generation and better spectral response.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.405-407
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• 2004

We have optimized the low temperature growth of microcrystalline silicon at 80$^{\circ}C$. This material has been used to fabricate bottom gate ${\mu}c$-Si:H TFTs by using a layer-by-layer nitrogenation process. By using this process the amorphous incubation layer can be converted into silicon nitride and leads to an increase in field effect mobility of the TFT

• Journal of the Korean Ceramic Society
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• v.29 no.6
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• pp.451-458
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• 1992

Dense glass-ceramics for low firing temperature substrate were prepared by addition of CeO2 flux to the glass of MgO-Al2O3-SiO2 system. Glass powders were fabricated by melting at 150$0^{\circ}C$ and ball milling. Glass powder compacts were sintered at 800~100$0^{\circ}C$ for 3h. The crystallization and the shrinkage behaviors of glass powder compacts were analyzed by XRD, DTA and TMA. The shrinkage of glass powder compact increased with increasing the amount of CeO2. Because the softening temperature decreased and the crystallization temperature increased with increasing the amount of CeO2. Apparently, addition of CeO2 prevented formation of $\mu$-cordierite phase from the glass-ceramics and improved formation of $\alpha$-cordierite phase. Therefore crystallization properties were enhanced.