• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.365-365
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• 2010

In this paper, silicon nitride thin films with different silane and ammonia gas ratios were deposited and characterized for the antireflection and passivation layer of high efficiency single crystalline silicon solar cells. As the flow rate of the ammonia gas increased, the refractive index decreased and the band gap increased. Consequently, the transmittance increased due to the higher band gap and the decrease of the defect states which existed for the 1.68 and 1.80 eV in the SiNx films. The reduction in the carrier lifetime of the SiNx films deposited by using a higher $NH_3/SiH_4$ flow ratio was caused by the increase of the interface traps and the defect states in/on the interface between the SiNx and the silicon wafer. The silicon and nitrogen rich films are not suitable for generating both higher carrier lifetimes and transmittance. These results indicate that the band gap and the defect states of the SiNx films should be carefully controlled in order to obtain the maximum efficiency for c-Si solar cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.6
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• pp.370-375
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• 2016

In this paper, we investigated the electrical properties of crystalline silicon solar cell fabricated with Ni/Cu/Ag plating. The laser process was used to ablate silicon nitride layer as well as to form the selective emitter. Phosphoric acid layer was spin-coated to prevent damage caused by laser and formed selective emitter during laser process. As a result, the contact resistance was decreased by lower sheet resistance in electrode region. Low sheet resistance was obtained by increasing laser current, but efficiency and open circuit voltage were decreased by damage on the wafer surface. KOH treatment was used to remove the laser damage on the silicon surface prior to metalization of the front electrode by Ni/Cu/Ag plating. Ni and Cu were plated for each 4 minutes and 16 minutes and very thin layer of Ag with $1{\mu}m$ thickness was plated onto Ni/Cu electrode for 30 seconds to prevent oxidation of the electrode. The silicon solar cells with KOH treatment showed the 0.2% improved efficiency compared to those without treatment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.1
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• pp.23-28
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• 2023

This paper demonstrates a novel NAND flash memory structure and annealing configuration including through-silicon via (TSV) inside the silicon substrate to improve annealing efficiency using an electro-thermal annealing (ETA) technique. Compared with the conventional ETA which utilizes WL-to-WL current flow, the proposed annealing method has a higher annealing temperature as well as more uniform heat distribution, because of thermal isolation on the silicon substrate. In addition, it was found that the annealing temperature is related to the electrical and thermal conductivity of the TSV materials. As a result, it is possible to improve the reliability of NAND flash memory. All the results are discussed based on 3-dimensional (3-D) simulations with the aid of the COMSOL simulator.

• Journal of the Korean Solar Energy Society
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• v.32 no.spc3
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• pp.194-198
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• 2012

Crystalline silicon solar cell remains the major player in the photovoltaic marketplace with 80% of the market, despite the development of various thin film technologies. Silicon's excellent efficiency, stability, material abundance and low toxicity have helped to maintain its position of dominance. However, the cost of silicon materials remains a major barrier to reducing the cost of silicon photovoltaics. Using the crystalline silicon wafer with thinner thickness is the promising way for cost and material reduction in the solar cell production. However, the thinner the silicon wafer is, the worse bow phenomenon is induced. The bow phenomenon is observed when two or more layers of materials with different temperature expansion coefficiencies are in contact, in this case silicon and aluminum. In this paper, the solar cells were fabricated with different thicknesses of Al layer in order to reduce the bow phenomenon. With less amount of paste applications, we observed that the bow could be reduced by up to 40% of the largest value with 120 micron thickness of the wafer even though the conversion efficiency decrease by 0.5% occurred. Since the bowed wafers lead to unacceptable yield losses during the module construction, the reduction of bow is indispensable on thin crystalline silicon solar cell. In this work, we have studied on the counterbalance between the bow and conversion efficiency and also suggest the formation of enough back surface field (BSF) with thinner Al layer application.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.4
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• pp.292-297
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• 2003

We fabricated a single crystal silicon thin film transistor for active matrix organic light emitting displays(AMOLEDs) using silicon on insulator wafer (SOI wafer). Poly crystal silicon thin film transistor(poly-Si TFT) Is actively researched and developed nowsdays for a pixel switching devices of AMOLEDs. However, poly-Si TFT has some disadvantages such as high off-state leakage currents and low field-effect mobility due to a trap of grain boundary in active channel. While single crystal silicon TFT has many advantages such as high field effect mobility, low off-state leakage currents, low power consumption because of the low threshold voltage and simultaneous integration of driving ICs on a substrate. In our experiment, we compared the property of poly-Si TFT with that of SOI TFT. Poly-Si TFT exhibited a field effect mobility of 34 $\textrm{cm}^2$/Vs, an off-state leakage current of about l${\times}$10$\^$-9/ A at the gate voltage of 10 V, a subthreshold slope of 0.5 V/dec and on/off ratio of 10$\^$-4/, a threshold voltage of 7.8 V. Otherwise, single crystal silicon TFT on SOI wafer exhibited a field effect mobility of 750 $\textrm{cm}^2$/Vs, an off-state leakage current of about 1${\times}$10$\^$-10/ A at the gate voltage of 10 V, a subthreshold slope of 0.59 V/dec and on/off ratio of 10$\^$7/, a threshold voltage of 6.75 V. So, we observed that the properties of single crystal silicon TFT using SOI wafer are better than those of Poly Si TFT. For the pixel driver in AMOLEDs, the best suitable pixel driver is single crystal silicon TFT using SOI wafer.

• Journal of the Korean Solar Energy Society
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• v.39 no.1
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• pp.1-9
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• 2019

Light induced degradation is one of the major research challenges of hydrogenated amorphous silicon related thin film silicon solar cells. Amorphous silicon shows creation of metastable defect states, originating from elevated concentration of dangling bonds during light exposure. The metastable defect states work as recombination centers, and mostly affects quality of intrinsic layer in solar cells. In this paper we present results of light induced degradation in thin film silicon solar cells and discussion on physical origin, mechanism and practical solutions of light induced degradation in thin film silicon solar cells. In-situ light-soaking IV measurement techniques are presented. We also present thin film silicon material with silicon nano-quantum dots embedded within amorphous matrix, which shows superior stability during light-soaking. Our results suggest that solar cell using silicon nano-quantum dots in abosrber layer shows superior stability under light soaking, compared to the conventional amorphous silicon solar cell.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.10a
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• pp.187-187
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• 1997

Silicon nitride is the most excellent materials among structural ceramics. It has been reported that fracture toughness was improved with adding second phase particles, whisker, fiber etc. However, containing of second phase particles enhanced fracture toughness, however flexural strength was degraded. As adding nanosize SiC particles into silicon nitride, the physical properties of fluxural strength, fracture toughness, the modulus of elasticity. In this study, 2wt% $Al_2$O$_3$ and 4 wt% $Y_2$O$_3$ were added into UBE E-10 and 0, 10, 20, 30, 40, 50 vol% nano-SiC powder (Sumitomo T1 powder) were added, respectively. It is hot pressed at 185$0^{\circ}C$ for 1 hour. Most of structural ceramics for engineering application are wear resistance. In this study, wear behaviors (in water) of silicon nitride with varying the amount of nano-size silicon carbide were investigated, and was compared to physical properties. Simultaneously wear mechanism will be found out.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1719-1721
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• 2012

We have investigated the $H_2$ adsorption structures and binding energies of the metal (M)-doped (M = Li, Na, K, Mg, and Al) silicon complexes, $M-Si_{19}H_{11}$ and $M-Si_{24}H_{12}$, using density functional calculations. Alkali metals are preferred as doping elements because the Mg-Si and Al-$H_2$ interactions are weak. The maximum numbers of $H_2$ molecules that can be adsorbed are four and five for M=Li and K, respectively. We propose that the K-decorated silicon material might be an effective hydrogen storage material with high hydrogen capacity and high reversibility.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.39-39
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• 2009

We fabricated p-channel TFTs based on poly Silicon. The 35nm thickness silicon dioxide layer structure got higher $I_{on}/I_{off}$ ratio, field-effect Mobility and output current than 10nm thickness. And 35nm layer showed low leakage current and threshold voltage. So, 35nm thickness silicon dioxide layer TFTs are faster reaction speed and lower power consumption than 10nm thickness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.270-270
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• 2009

The surface texturing technology is one of the methods to improve the efficiency of crystalline silicon solar cell. This process reduced the reflectance at the surface by the so-called double bounce effect and increased the light trapping. Among these surface texturing technology, the laser texturing is effective for multi-crystalline silicon solar cells which have random crystallographic directions. We investigated the characteristics of laser processing on the surface of the multi-crystalline silicon solar cells using the fiber laser.