• Journal of Korean Vacuum Science & Technology
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• v.6 no.3
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• pp.120-125
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• 2002

The aim of the present work is to optimized the annealing parameter in both front and back screen printed contacts realization on p-type multicrystalline silicon and with phosphorus diffused. The RTA treatments were carried out at various temperatures from 600 to 850$\^{C}$ and annealing time ranging from 3 min to 5 min in air, O$_2$and N$_2$ ambiance. The contacts parameters are obtained according to Transmission Line Model measurements. A good RTA cycle is obtained with a temperature plateau of 700$\^{C}$-750$\^{C}$ and annealing ambiance of air. Several processing parameters required for good cell efficiency are discussed with an emphasis placed on the critical role of the glass frit in the aluminum paste. A anamolus behaviour of Aluminum n-doping on p-type Si wafer, contact at high temperature have also been studied.

• 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.

• Journal of the Korean Solar Energy Society
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• v.38 no.1
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• pp.45-55
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• 2018

Environmentally benign lead-free solder coated ribbon (e. g. SnCu, SnZn, SnBi${\cdots}$) has been intensively studied to interconnect cells without lead mixed ribbon (e. g. SnPb) in the crystalline silicon(c-Si) photovoltaic modules. However, high melting point (> $200^{\circ}C$) of non-lead based solder provokes increased thermo-mechanical stress during its soldering process, which causes early degradation of PV module with it. Hence, we proposed low-temperature conductive paste (CP) based tabbing method for lead-free ribbon. Modules, interconnected by the lead-free solder (SnCu) employing CP approach, exhibits similar output without increased resistivity losses at initial condition, in comparison with traditional high temperature soldering method. Moreover, 400 cycles (2,000 hour) of thermal cycle test reveals that the module integrated by CP approach withstands thermo-mechanical stress. Furthermore, this approach guarantees strong mechanical adhesion (peel strength of ~ 2 N) between cell and lead-free ribbons. Therefore, the CP based tabbing process for lead free ribbons enables to interconnect cells in c-Si PV module, without deteriorating its performance.

• Journal of Ceramic Processing Research
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• v.13 no.spc1
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• pp.140-144
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• 2012

Ga-doped ZnO (GZO) was a limit of application on the photovoltaic devices such as CIGS, CdTe and DSSC requiring high process temperature, because it's electrical resistivity is unstable above 300 ℃ at atmosphere. Therefore, ZTO (zinc tin oxide) was introduced in order to improve permeability and thermal stability of GZO film. The resistivity of GZO (300 nm) single layer increased remarkably from 1.8 × 10-3Ωcm to 5.5 × 10-1Ωcm, when GZO was post-annealed at 400 ℃ in air atmosphere. In the case of the ZTO (150 nm)/GZO (150 nm) double layer, resistivity showed relatively small change from 3.1 × 10-3Ωcm (RT) to 1.2 × 10-2Ωcm (400 ℃), which showed good agreement with change of carrier density. This result means that ZTO upper layer act as a barrier for oxygen at high temperature. Also ZTO (150 nm)/GZO (150 nm) double layer showed lower WVTR compared to GZO (300 nm) single layer. Because ZTO has lower WVTR compared to GZO, ZTO thin film acts as a barrier by preventing oxygen and water molecules to penetrate on top of GZO thin film.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.111-115
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• 2015

To improve the efficiency of the Si solar cell, high minority carrier life time is required. Therefore, the passivation technology is important to eliminate point defects on the silicon surface, causing the loss of minority carrier recombination. PECVD or post-annealing of thermally-grown $SiO_2$ is commonly used to form the passivation layer, but a high-temperature process and low thermal stability is a critical factor of low minority carrier lifetime. In this study, atomic layer deposition was used to grow the $Al_2O_3$ passivation layer at low temperature process. $Al_2O_3$ was selected as a passivation layer which has a low surface recombination velocity because of the fixed charge density. For the high charge density, an improved minority carrier lifetime, and a low surface recombination, nitrogen was doped in the $Al_2O_3$ thin film and the improvement of passivation was studied.

• KIEAE Journal
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• v.14 no.6
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• pp.99-104
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• 2014

Recently supply of low energy house is increasing which can enhance energy efficiency and indoor environment comfort. Low energy house have to secure air tightness as well as thermal performance so house become high airtightness and inevitably need heat recovery ventilator to enhance indoor air quality. However, most of current ventilation systems are one-click, controlling the entire space so it causes increasing of heating load and fan power which makes it hard to save energy. Thus, Individual Control system is required which can achieve both enhancing indoor air quality and decreasing heating load and electric fan power. Thereby, in this study, we analyzed the correlation between ventilation and fan power through mock-up experiment and measured ventilation load under individual control system. As a result, under the condition of $24^{\circ}C$ of indoor temperature for 6 month(November to April) in Daejeon, ventilation load by fan speed was $10.9{\sim}19.6kWh/m^2{\cdot}a$ when operated 24 hours and $7.6{\sim}13.7kWh/m^2{\cdot}a$ when operated 12 hours in night time. In addition, it is possible to reduce at most 60% of ventilation load under the individual control system; measured ventilation load was $7.4kWh/m^2{\cdot}a$ when operated 24 hours, and $5.5kWh/m^2{\cdot}$ when operated 12 hours in night time.

• Korean Journal of Materials Research
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• v.22 no.10
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• pp.531-538
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• 2012

Hollow silica spheres were prepared by spray drying of precursor solution of colloidal silica. The precursor solution is composed of 10-20 nm colloidal silica dispersed in a water or ethanol-water mixture solvent with additives of tris hydroxymethyl aminomethane. The effect of pH and concentrations of the precursor and additives on the formation of hollow sphere particles was studied. The spray drying process parameters of the precursor feeding rate, inlet temperature, and gas flow rate are controlled to produce the hollow spherical silica. The mixed solvent of ethanol and water was preferred because it improved the hollowness of the spheres better than plain water did. It was possible to obtain hollow silica from high concentration of 14.3 wt% silica precursor with pH 3. The thermal conductivity and total solar reflectivity of the hollow silica sample was measured and compared with those values of other commercial insulating fillers of glass beads and $TiO_2$ for applications of insulating paint, in which the glass beads are representative of the low thermal conductive fillers and the $TiO_2$ is representative of infrared reflective fillers. The thermal conductivity of hollow silica was comparable to that of the glass beads and the total solar reflectivity was higher than that of $TiO_2$.

• Journal of the Korean institute of surface engineering
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• v.49 no.1
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• pp.54-61
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• 2016

Screen printing of commercially available Ag paste is the most widely used method for the front side metallization of Si solar cells. However, the metallization using Ag paste is expensive and needs high temperature annealing for reliable contact. Among many metallization schemes, Ni/Cu/Sn plating is one of the most promising methods due to low contact resistance and mass production, resulting in high efficiency and low production cost. Ni layer serves as a barrier which would prevent copper atoms from diffusion into the silicon substrate. However, Ni based schemes by electroless deposition usually have low thermal stability, and require high annealing process due to phosphorus content in the Ni based films. These problems can be resolved by adding W element in Ni-based film. In this study, Ni-W-P alloys were formed by electroless plating and properties of it such as sheet resistance, resistivity, specific contact resistivity, crystallinity, and morphology were investigated before and after annealing process by means of transmission line method (TLM), 4-point probe, X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.788-791
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• 2002

Tin doped indium oxide(ITO) films are highly conductive and transparent in the visible region whose property leads to the applications in solar cell, liquid crystal display, thermal heater, and other sensors. This paper investigated ITO films as a transparent conducting films for application of PDP. ITO films were grown on glass substrate by RF magnetron sputtering method. To achieve high transmittance and low resistivity, we examined the various film deposition such as substrate temperature, gas pressure, annealing temperature, and deposition time. We recommend the substrate temperature of $500^{\circ}C$ and post annealing of $200^{\circ}C$ in $O_2$ atmosphere for good conductivity and transmittance. From XRD examination, ITO films showed a preferred(222) orientation. As substrate temperature increased from RT to $500^{\circ}C$, the intensity of the (222) peak increased. The highest peak intensity was observed at a substrate temperature of $500^{\circ}C$. with the optimum growth conditions, ITO films showed resistivity of $1.04{\times}10^{-4}{\Omega}-cm$ and transmittance of 81.2% for a film 300nm thick in the wavelength range of the visible spectrum.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.365.1-365.1
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• 2014

Cobalt oxide has excellent various properties such as high catalytic activity, antiferromagnetism, and electrochromism. So cobalt oxides offer a great potential for their applications in the various areas such as optical gas sensor, catalysts for oxidation reaction, electrochromic devices, high temperature solar selective absorbers, magnetic materials, pigment for glasses and ceramics, and negative electrodes for lithium-ion batteries. We have synthesized novel cobalt complexes by simple reaction of cobalt bistrimethylsilylamide as a starting material with a lot of conventional ligands as potential cobalt oxide precursors. The studies include the facile preparation, structural characterization, and spectroscopic analysis of the new precursors. We are making efforts to grow cobalt oxide thin films using cobalt complexes newly synthesized in this study using deposition techniques.