• Korean Journal of Materials Research
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• v.23 no.1
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• pp.35-40
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• 2013

In this study, the influence on the surface passivation properties of crystalline silicon according to silicon wafer thickness, and the correlation with a-Si:H/c-Si heterojunction solar cell performances were investigated. The wafers passivated by p(n)-doped a-Si:H layers show poor passivation properties because of the doping elements, such as boron(B) and phosphorous(P), which result in a low minority carrier lifetime (MCLT). A decrease in open circuit voltage ($V_{oc}$) was observed when the wafer thickness was thinned from $170{\mu}m$ to $50{\mu}m$. On the other hand, wafers incorporating intrinsic (i) a-Si:H as a passivation layer showed high quality passivation of a-Si:H/c-Si. The implied $V_{oc}$ of the ITO/p a-Si:H/i a-Si:H/n c-Si wafer/i a-Si:H/n a-Si:H/ITO stacked layers was 0.715 V for $50{\mu}m$ c-Si substrate, and 0.704 V for $170{\mu}m$ c-Si. The $V_{oc}$ in the heterojunction solar cells increased with decreases in the substrate thickness. The high quality passivation property on the c-Si led to an increasing of $V_{oc}$ in the thinner wafer. Short circuit current decreased as the substrate became thinner because of the low optical absorption for long wavelength light. In this paper, we show that high quality passivation of c-Si plays a role in heterojunction solar cells and is important in the development of thinner wafer technology.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.7
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• pp.33-39
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• 2015

In this work, SU-8 passivated IZO thin-film transistors(TFTs) made by solution-processes was investigated for enhancing stability of indium zinc oxide(IZO) TFT. A very viscous negative photoresist SU-8, which has high mechanical and chemical stability, was deposited by spin coating and patterned on top of TFT by photo lithography. To investigate the enhanced electrical performances by using SU-8 passivation layer, the TFT devices were analyzed by X-ray phtoelectron spectroscopy(XPS) and Fourier transform infrared spectroscopy(FTIR). The TFTs with SU-8 passivation layer show good electrical characterestics, such as ${\mu}_{FE}=6.43cm^2/V{\cdot}s$, $V_{th}=7.1V$, $I_{on/off}=10^6$, SS=0.88V/dec, and especially 3.6V of ${\Delta}V_{th}$ under positive bias stress (PBS) for 3600s. On the other hand, without SU-8 passivation, ${\Delta}V_{th}$ was 7.7V. XPS and FTIR analyses results showed that SU-8 passivation layer prevents the oxygen desorption/adsorption processes significantly, and this feature makes the effectiveness of SU-8 passivation layer for PBS.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.99.2-99.2
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• 2010

This paper investigates the dependence of a-Si:H/c-Si passivation and heterojunction solar cell performances on various cleaning processes of silicon wafer and surface morphology. It is observed that passivation quality of a-Si:H thin-films on c-Si wafer highly depends on wafer surface conditions. The MCLT(Minority carrier life time) of wafer incorporating intrinsic (i) a-Si:H as a passivation layer shows sensitive variation with cleaning process and surface morpholgy. By applying improved cleaning processes and surface morphology we can obtain the MCLT of $200{\mu}sec$ after H-termination and above 1.5msec after i a-Si:H thin film deposition, which has implied open circuit voltage of 0.720V.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.5
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• pp.341-344
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• 2018

In order to achieve a high efficiency for the silicon solar cell, a passivation characteristic that minimizes the electrical loss at a silicon interface is required. In this paper, we evaluated the applicability of the oxide film formed by ozone for the tunnel silicon oxide film. To this end, we fabricated the silicon oxide film by changing the condition of ozone oxidation and compared the characteristics with the oxide film formed by the existing nitric acid solution. The ozone oxidation was formed in the temperature range of $300{\sim}500^{\circ}C$ at an ozone concentration of 17.5 wt%, and the passivation characteristics were compared. Compared to the silicon oxide film formed by nitric acid oxidation, implied open circuit voltage (iVoc) was improved by ~20 mV in the ozone oxidation and the ozone oxidation after the nitric acid pretreatment was improved by ~30 mV.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.334.2-334.2
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• 2016

Silicon nitride (SiNx:H) films are generally used as passivation layer on solar cell and they are usually made by plasma enhanced chemical vapor deposition (PECVD). In this study, we investigated the properties of silicon nitride (SiNx:H) films made by PECVD. Effects of mixture ratio of process gases with silane (SiH4) and ammonia (NH3) on the passivation qualities of silicon nitride film are evaluated. Passivation properties of SiNx:H are focused by making antireflection properties identical with thickness and refractive index controlled. The absorption coefficient of each film was evaluated by spectrometric ellipsometery and the minority carrier lifetimes were evaluated by quasi-steady-state photo-conductance (QSSPC) measurement. The optical properties were obtained by UV-visible spectrophotometer. The interface properties were measured by capacitance-voltage (C-V) measurement and the film components were identified by Fourier transform infrared spectroscopy (FT-IR) and Rutherford backscattering spectroscopy detection (RBS) - elastic recoil detection (ERD).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.438-438
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• 2009

We have investigated the effect of forming gas annealing for Upgraded Metallurgical Grade (UMG)-silicon solar cell in order to obtain low-cost high-efficiency cell using post deposition anneal at a relatively low temperature. We have observed that high concentration hydrogenation effectively passivated the defects and improved the minority carrier lifetime, series resistance and conversion efficiency. It can be attributed to significantly improved hydrogen-passivation in high concentration hydrogen process. This improvement can be explained by the enhanced passivation of silicon solar cell with antireflection layer due to hydrogen re-incorporation. The results of this experiment represent a promising guideline for improving the high-efficiency solar cells by introducing an easy and low cost process of post hydrogenation in optimized condition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.332-333
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• 2009

In this paper, we have deposited silicon nitride films by plasma-enhanced chemical vapor deposition (PECVD). For films deposited under optimized conditions, the mechanism of plasma-enhanced vapor deposition of silicon nitride is studied by varying process parameters such as rf power, gas ratio, and chamber pressure. It was demonstrated that organic light-emitting diode(OLEDs) were fabricated with the inorganic passivation layer processing. We have been studied the inorganic film encapsulation effect for organic light-emitting diodes (OLED). To evaluate the passivation layer, we have carried out the fabrication of OLEDs and investigate with luminescence and MOCON.

• Electrical & Electronic Materials
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• v.10 no.5
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• pp.473-480
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• 1997

Surface passivation using glass powders results in good reliability for high voltage silicon power devices. In this paper Zinc borosilicate glass and Lead borosilicate glass were prepared for the purpose of passivating, and a deposition technique of glass films on the silicon surface by electrophoresis in which acetone is used as a suspension medium has been investigated. Their physical properties were compared using DTA, SEM, XRD, as a function of firing temperature, I can get the fine films of 22${\mu}{\textrm}{m}$ thickness with Lead borosilicate glass under 300 volts applied, 3 minutes and $700^{\circ}C$ firing temperature. Also I can get the fine films of 17${\mu}{\textrm}{m}$ thickness with Zinc borosilicate glass under same conditions. As a result of investigation of glass films from which glass layer was removed by placing it in HCl, it has been found that pre-firing and annealing play an important role to achieve uniform and fine glass deposition films. And also it was found that relative dielectric constant is independence of frequency.

• The Korean Journal of Ceramics
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• v.3 no.2
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• pp.92-95
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• 1997

Because of the novel characteristics such as chemical stability, hardness, electrical resistivity and thermal conductivity, diamond-like carbon (DLC) film is a suitable material for the passivation layers. For this purpose, using the PECVD, DLC films were synthesized at room temperature. The adhesion and the hardness of the DLC films deposited on Si an SiO2 substrate were measured. The resistivity of 5.3$\times$$10^8$$\Omega$.cm was measured by automatic spreading resistance probe analysis method. The thermal conductivities of different DLC films were measured and compared with that of phospho silicate glass (PSG) film which is commonly used as passivation layers. The thermal conductivity of DLC film was improved by increasing hydrogen flow rate up to 90 sccm and was better than that of PSG film. The patterning techniques of the DLC film developed using the RIE and the lift-off method to form 5$\mu\textrm{m}$ line. Finally, the thermal characteristics of the power transistor with the DLC film as passiviation layer was analyzed.

• Journal of the Korean institute of surface engineering
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• v.43 no.6
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• pp.272-277
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• 2010

We investigated the life time characteristics of OLED device with aluminium oxide ($AlO_x$) passivation film on glass substrate and polyethylene terephthalate (PET) substrate by RF magnetron sputtering for the transparent barrier film applied to flexible OLED device. Basic buffer layer was determined as $Alq_3$(500 nm)-LiF(300 nm)-Al(1200 nm), and the most suitable aluminium oxide ($AlO_x$) film have been formed when the partial volume ratio of oxygen was 20% and the sputtering power was 100 watt and the minimum thickness of buffer was $2\;{\mu}m$. $AlO_x$/epoxy hybrid film was also used as a effective passivation layer for the purpose of improving life time characteristics of OLED devices with the glass substrate and the plastic substrate. Besides, the simultaneous deposition of $AlO_x$/epoxy film on back side of PET could result in better improvement of life time.