• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.519-524
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• 2019

Even though stainless steel foil is not a highly efficient material for film-type solar cell, it has strong passivation capability without additional process. In this study, silicone resin was employed during a-Si:H thin film solar cell fabrication for the purpose of planarization and electrical insulation. In the first stage of process, silicone resin was coat onto the stainless steel (STS) using spin coater with thickness of $2{\sim}3{\mu}m$ and followed by aluminum deposition using ion beam application. Unexpectedly buckling was formed during aluminum deposition process. After subsequent fabrication processes, solar cell performance was evaluated. In voltage-current data, slight increase of cell performance was obtained and interpreted by the increase of light scattering.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.267-267
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• 2010

The structural and electrical properties of microcrystalline silicon films were investigated by hot wire chemical vapor deposition(HWCVD) often called catalytic chemical vapor deposition(Cat-CVD). The Si microcrystalline phase is easily controlled by changing the rate of the silane concentration of $SiH_4$ to $H_2$ during deposition. The Structural property was observed by Raman and SEM. Photo-conductivity and dark conductivity, and photo-sensitivity were observed by Sunsimulator (AM 1.5 illumination). The film color was changed by the variation of silane concentration. HWCVD is useful for the formation of Si thin films for solar cell and needs further commercialized development for mass production.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.1
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• pp.53-60
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• 2014

Different kinds of post-deposition annealing (PDA) by a rapid thermal process (RTP) are used to enhance the field-effect passivation of $Al_2O_3$ film in crystal Si solar cells. To characterize the effects of PDA on $Al_2O_3$ and the interface, metal-insulator semiconductor (MIS) devices were fabricated. The effects of PDA were characterized as functions of RTP temperature from $400{\sim}700^{\circ}C$ and RTP time from 30~120 s. A high temperature PDA can retard the passivation of thin $Al_2O_3$ film in c-Si solar cells. PDA by RTP at $400^{\circ}C$ results in better passivation than a PDA at $400^{\circ}C$ in forming gas ($H_2$ 4% in $N_2$) for 30 minutes. A high thermal budget causes blistering on $Al_2O_3$ film, which degrades its thermal stability and effective lifetime. It is related to the film structure, deposition temperature, thickness of the film, and annealing temperature. RTP shows the possibility of being applied to the PDA of $Al_2O_3$ film. Optimal PDA conditions should be studied for specific $Al_2O_3$ films, considering blistering.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1555-1558
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• 2002

This paper presents deposition and characterizations of microcrystalline silicon(${\mu}c$-Si:H) films prepared by hot wire chemical vapor deposition at substrate temperature below $300^{\circ}C$. The $SiH_4$ Concentration$[F(SiH_4)/F(SiH_4)+F(H_2)]$ is critical parameter for the formation of Si films with microcrystalline phase. At 6% of silane concentration, deposited intrinsic ${\mu}c$-Si:H films shows sufficiently low dark conductivity and high photo sensitivity for solar cell applications. P-type ${\mu}c$-S:H films deposited by Hot-Wire CVD also shows good electrical properties by varying the rate of $B_2H_6$ to $SiH_4$ gas. The solar cells with structure of Al/nip ${\mu}c$-Si:H/TCO/glass was fabricated with sing1e chamber Hot-Wire CVD. About 3% solar efficiency was obtained and applicability of HWCVD for thin film solar cells was proven in this research.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.5
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• pp.237-241
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• 2004

Amorphous silicon (a-Si) films are used in a broad range of solar cell, flat panel display, and sensor. Because of the greater ease of deposition and lower processing temperature, thin films are widely used for thin film transistors (TFTs). However, they have lower stability under the exposure of visible light and because of their low field effect mobility ($\mu$$_{FE}$ ) , less than 1 c $m^2$/Vs, they require a driving IC in the external circuits. On the other hand, polycrystalline silicon (poly-Si) thin films have superiority in $\mu$$_{FE}$ and optical stability in comparison to a-Si film. Many researches have been done to obtain high performance poly-Si because conventional methods such as excimer laser annealing, solid phase crystallization and metal induced crystallization have several difficulties to crystallize. In this paper, a new crystallization process using a molybdenum substrate has been proposed. As we use a flexible substrate, high temperature treatment and roll-to-roll process are possible. We have used a high temperature process above 75$0^{\circ}C$ to obtain poly-Si films on molybdenum substrates by a rapid thermal annealing (RTA) of the amorphous silicon (a-Si) layers. The properties of high temperature crystallized poly-Si studied, and poly-Si has been used for the fabrication of TFT. By this method, we are able to achieve high crystal volume fraction as well as high field effect mobility.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.310.1-310.1
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• 2013

We show the novel hot electron based-solar energy conversion using tandem structured Schottky diode with double Schottky barriers. In this report, we show the effect of the double Schottky barriers on solar cell performance by enhancing both of internal photoemission and band-to-band excitation. The tandem structured Au/Si diode capped with TiO2 layer as second semiconductor exhibited improved ability for light harvesting. The proposed mechanisms consist of multiple reflections of hot electrons and additional pathway of solar energy conversion due to presence of multiple interfaces between thin gold film and semiconductors. Short-circuit photocurrent measured on the tandem structured Au/Si diodes under illumination of AM1.5 increased by approximately 70% from 3.1% to 5.3% and overall incident photon to electron conversion efficiency (IPCE) was enhanced in visible light, revealing that the concept of the double Schottky barriers have significant potential as novel strategy for light harvesting.

• Korean Journal of Materials Research
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• v.29 no.11
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• pp.715-719
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• 2019

Molybdenum is a low-resistivity transition metal that can be applied to silicon devices using Si-metal electrode structures and thin film solar cell electrodes. We investigate the deposition of metal Mo thin film by plasma-enhanced atomic layer deposition (PE-ALD). $Mo(CO)_6$ and $H_2$ plasma are used as precursor. $H_2$ plasma is induced between ALD cycles for reduction of $Mo(CO)_6$ and Mo film is deposited on Si substrate at $300^{\circ}C$. Through variation of PE-ALD conditions such as precursor pulse time, plasma pulse time and plasma power, we find that these conditions result in low resistivity. The resistivity is affected by Mo pulse time. We can find the reason through analyzing XPS data according to Mo pulse time. The thickness uniformity is affected by plasma power. The lowest resistivity is $176{\mu}{\Omega}{\cdot}cm$ at $Mo(CO)_6$ pulse time 3s. The thickness uniformity of metal Mo thin film deposited by PE-ALD shows a value of less than 3% below the plasma power of 200 W.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.10
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• pp.754-759
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• 2013

Aluminum oxide($Al_2O_3$) film deposited by atomic layer deposition (ALD) is known to supply excellent surface passivation properties on crystalline Si surfaces. Since $Al_2O_3$ has fixed negative charge, it forms effective surface passivation by field effect passivation on the rear side in p-type silicon solar cell. However, $Al_2O_3$ layer formed by ALD process needs very long process time, which is not applicable in mass production of silicon solar cells. In this paper, plasma-assisted ALD(PA-ALD) was applied to form $Al_2O_3$ to reduce the process time. $Al_2O_3$ synthesized by ALD on c-Si (100) wafers contains a very thin interfacial $SiO_2$ layer, which was confirmed by FTIR and TEM. To improve passivation quality of $Al_2O_3$ layer, the deposition temperature was changed in range of $150{\sim}350^{\circ}C$, then the annealing temperature and time were varied. As a result, the silicon wafer with aluminum oxide film formed in $250^{\circ}C$, $400^{\circ}C$ and 10 min for the deposition temperature, the annealing temperature and time, respectively, showed the best lifetime of 1.6ms. We also observed blistering with nanometer size during firing of $Al_2O_3$ deposited on p-type silicon.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.242-242
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• 2010

산화 알루미늄($Al_2O_3$) 박막을 p-type Czochralski(CZ) Si 위에 Remote Plasma Atomic Layer Deposition(RPALD)을 이용하여 저온 공정으로 증착하였다. Photolithography 공정으로 grid 패턴을 형성한 후 열 증착기로 알루미늄을 증착하여 MIS-IL (Metal-Insulator-Semiconductor Inversion Layer) solar cell을 제작하였다. 반응소스로는 Trimethylaluminum (TMA)과 $O_2$를 이용하였다. $Al_2O_3$ 박막의 전기적 특성 평가를 위해 MIS capacitor를 제작하여 Capacitance-voltage (C-V), Current-voltage (I-V), Interface state density ($D_{it}$)를 평가하였으며 Solar simulator를 이용하여 MIS-IL Solar cell의 Efficiency을 측정하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.28-28
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• 2009

Fabrications of antireflection structures on solar cell were investigated to trap the light and to improve quantum efficiency. Introductions of patterned substrate or textured layer for Si solar cell were performed to prevent reflectance and to increase the path length of incoming light. However, it is difficult to deposit conformally flat electrode on perpendicular plane. ZnO is II-VI compound semiconductor and well-known wide band-gap material. It has similar electrical and optical properties as ITO, but it is nontoxic and stable. In this study, Al-doped ZnO thin films are deposited as transparent electrode by atomic layer deposition method to coat on Si substrate with micro-scale structures. The deposited AZO layer is flatted on horizontal plane as well as perpendicular one with conformal 200 nm thickness. The carrier concentration, mobility and resistivity of deposited AZO thin film on glass substrate were measured $1.4\times10^{20}cm^{-3}$, $93.3cm^2/Vs$, $4.732\times10^{-4}{\Omega}cm$ with high transmittance over 80%. The AZO films were coated with polyimide and performed selective polyimide stripping on head of column by reactive ion etching to measure resistance along columns surface. Current between the micro-columns flows onto the perpendicular plane of deposited AZO film with low resistance.