• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.418.2-418.2
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• 2016

$Al_2O_3$ passivation layer has excellent passivation properties at p-type Si surface. This $Al_2O_3$ layer forms thin $SiO_2$ layer at the interface. There were some studies about inserting thermal oxidation process to replace naturally grown oxide during $Al_2O_3$ deposition. They showed improving passivation properties. However, thermal oxidation process has disadvantage of expensive equipment and difficult control of thin layer formation. Wet chemical oxidation has advantages of low cost and easy thin oxide formation. In this study, $Al_2O_3$/$SiO_2/Si(100)$ interface was formed by wet chemical oxidation and PA-ALD process. $SiO_2$ layer at Si wafer was formed by $HCl/H_2O_2$, $H_2SO_4/H_2O_2$ and $HNO_3$, respectively. 20nm $Al_2O_3$ layer on $SiO_2/Si$ was deposited by PA-ALD. This $Al_2O_3/SiO_2/Si(100)$ interface were characterized by capacitance-voltage characteristics and quasi-steady-state photoconductance decay method.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.110.1-110.1
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• 2012

Recently, advances in ZnO based oxide semiconductor materials have accelerated the development of thin-film transistors (TFTs), which are the building blocks for active matrix flat-panel displays including liquid crystal displays (LCD) and organic light-emitting diodes (OLED). However, the electrical performances of oxide semiconductors are significantly affected by interactions with the ambient atmosphere. Jeong et al. reported that the channel of the IGZO-TFT is very sensitive to water vapor adsorption. Thus, water vapor passivation layers are necessary for long-term current stability in the operation of the oxide-based TFTs. In the present work, $Al_2O_3$ and $TiO_2$ thin films were deposited on poly ether sulfon (PES) and $SnO_x$-based TFTs by electron cyclotron resonance atomic layer deposition (ECR-ALD). And enhancing the WVTR (water vapor transmission rate) characteristics, barrier layer structure was modified to $Al_2O_3/TiO_2$ layered structure. For example, $Al_2O_3$, $TiO_2$ single layer, $Al_2O_3/TiO_2$ double layer and $Al_2O_3/TiO_2/Al_2O_3/TiO_2$ multilayer were studied for enhancement of water vapor barrier properties. After thin film water vapor barrier deposited on PES substrate and $SnO_x$-based TFT, thin film permeation characteristics were three orders of magnitude smaller than that without water vapor barrier layer of PES substrate, stability of $SnO_x$-based TFT devices were significantly improved. Therefore, the results indicate that $Al_2O_3/TiO_2$ water vapor barrier layers are highly proper for use as a passivation layer in $SnO_x$-based TFT devices.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.299.2-299.2
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• 2013

We investigated the potassium remaining on a crystalline silicon solar cell after potassium hydroxide (KOH) etching and its effect on the lifetime of the solar cell. KOH etching is generally used to remove the saw damage caused by cutting a Si ingot; it can also be used to etch the rear side of a textured crystalline silicon solar cell before atomic layer-deposited Al2O3 growth. However, the potassium remaining after KOH etching is known to be detrimental to the efficiency of Si solar cells. In this study, we etched a crystalline silicon solar cell in three ways in order to determine the effect of the potassium remnant on the efficiency of Si solar cells. After KOH etching, KOH and tetramethylammonium hydroxide (TMAH) were used to etch the rear side of a crystalline silicon solar cell. To passivate the rear side, an Al2O3 layer was deposited by atomic layer deposition (ALD). After ALD Al2O3 growth on the KOH-etched Si surface, we measured the lifetime of the solar cell by quasi steady-state photoconductance (QSSPC, Sinton WCT-120) to analyze how effectively the Al2O3 layer passivated the interface of the Al2O3 layer and the Si surface. Secondary ion mass spectroscopy (SIMS) was also used to measure how much potassium remained on the surface of the Si wafer and at the interface of the Al2O3 layer and the Si surface after KOH etching and wet cleaning.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.430-430
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• 2012

The surface recombination velocity of the silicon solar cell could be reduced by passivation with insulating layers such as $SiO_2$, SiNx, $Al_2O_3$, a-Si. Especially, the aluminium oxide has advantages over other materials at rear surface, because negative fixed charge via Al vacancy has an additional back surface field effect (BSF). It can increase the lifetime of the hole carrier in p-type silicon. The aluminium oxide thin film layer is usually deposited by atomic layer deposition (ALD) technique, which is expensive and has low deposition rate. In this study, ICP-assisted reactive magnetron sputtering technique was adopted to overcome drawbacks of ALD technique. In addition, it has been known that by annealing aluminium oxide layer in nitrogen atmosphere, the negative fixed charge effect could be further improved. By using ICP-assisted reactive magnetron sputtering technique, oxygen to nitrogen ratio could be precisely controlled. Fabricated aluminium oxy-nitride (AlON) layer on silicon wafers were analyzed by x-ray photoelectron spectroscopy (XPS) to investigate the atomic concentration ratio and chemical states. The electrical properties of Al/($Al_2O_3$ or $SiO_2/Al_2O_3$)/Si (MIS) devices were characterized by the C-V measurement technique using HP 4284A. The detailed characteristics of the AlON passivation layer will be shown and discussed.

• 반도체디스플레이기술학회지
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• 제12권3호
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• pp.47-51
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• 2013

Current research trends of solar cells has focused on the high conversion efficiency and low-cost production technology. Passivation technology that can be easily adapted to mass production. Therefore, this study conducted experiments with aim of the following two methods for the fabrication of high-efficiency crystalline silicon solar cells. In the first task, an attempt is formation of local Al-BSF to a number of locally doped dots to increase the conversion efficiency of solar cells to reduce the loss of $V_{oc}$ overcome. The second major task, rear surface apply in $Al_2O_3/SiN_x$ stack layer, $Al_2O_3$ prominent negative fixed charge characteristics. As the result of task, Local Al-BSF and $Al_2O_3/SiN_x$ stack layer applied to the p-type single crystalline silicon solar cells, the average $V_{oc}$ of 644mV, $I_{sc}$ of 918mV and conversion efficiency of 18.70% were obtained.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.94-94
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• 2009

최근 실리콘 태양전지는 점점 얇아 지는 추세에 있다. 실리콘 태양전지에 있어 실리콘의 두께를 감소시키는 것은 실리콘 소모량을 줄이는데 있어 필수적인 조건이 되었다. 이에 따라 실리콘 표면의 passivation도 더욱 중요하게 여겨지고 있다. 실리콘 태양전지의 passivation막의 한 종류인 $Al_2O_3$는 다른 산화막 물질들과는 달리 negative fixed charge를 가지고 있고 charge의 양이 다른 산화막의 density보다 높아 p-type 실리콘의 경우 후면 passivation막으로 이용이 고려되고 있다. 본 연구에서는 atomic layer deposition으로 $Al_2O_3$막을 실리콘 위에 증착하여 열처리에 따른 그 특성을 비교하고 태양전지를 제작하였다. $Al_2O_3$막을 rapid thermal annealing을 통해 서로 다른 분위기에서 열처리 한 결과를 capacitance-voltage를 통해 측정하여 비교, 분석하였고 ellipsomety 분석을 통해 광학적 특성을 비교하였다. 또한 열처리 온도의 변화에 따른 $Al_2O_3$내에 charge에 변화가 있다는 것을 관찰하였다. 이러한 charge의 변화가 태양전지의 passivation에 영향을 주는지 관찰하기 위해 Quasi-steady state photoconductace를 통해 lifetime의 변화를 관찰 하였다. 이러한 실험결과로부터 열처리 분위기와 온도를 최적화 하여 태양전지 passivation 특성을 증가시킬 수 있었다.

• 한국표면공학회지
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• 제43권6호
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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.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2014년도 추계학술대회 논문집
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• pp.196-196
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• 2014

플라즈마 건식 식각 기술은 반도체 식각공정에서 효과적으로 이용되고 있으며, 반도체 소자의 크기가 줄어듬에 따라 미세하고 정확하게 식각 깊이를 제어할 수 있는 원자층 식각 기술이 개발되었다. 3-5족 반도체 소자의 Interface Passivation Layer 로 이용되는 $Al_2O_3$ 와 BeO 의 원자층 식각을 하였으며, 각각의 원자층 식각 조건과 식각 후의 표면 거칠기 변화에 대한 영향을 확인 할 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.689-689
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• 2013

Atomic layer deposition (ALD)에 의한 알루미늄 산화 막(Al2O3)은 고효율 결정질 실리콘 태양전지를 위한 우수한 표면 패시베이션 특성을 제공한다. 알루미늄 산화막는 고정적인 음전하를 가지고 있기 때문에 p-형 실리콘 태양 전지 후면은 전계에 의한 우수한 패시베이션 효과를 형성한다. 그러나, ALD 방식으로 증착된 알루미늄 산화막은 매우 긴 공정 시간을 필요로 하기 때문에 기존의 실리콘 태양 전지 공정에 적용하기가 어렵다. 본 논문에서는 알루미늄 산화막 형성에서 공정 시간을 줄이기 위해 Plasma assisted atomic layer deposition (PA-ALD) 방식을 적용했다. PA-ALD 기술은 trimethylaluminum (TMA)과 O2를 사용하여 기판 표면에 알루미늄 산화막을 증착하는 것으로 ALD 방식과 유사하지만, O2 플라즈마를 사용함으로써 증착 속도를 향상시킬 수 있다. 이는 좋은 패시베이션 특성을 가지는 알루미늄 산화막을 실리콘 태양전지양산 공정에 적용할 수 있는 가능성을 제시한다. PA-ALD 방식에 의한 알루미늄 산화막의 패시베이션 특성을 최적화하기 위해서 증착 후 열처리 조건에 대한 연구도 수행하였다. 막증착률이 1.1${\AA}$/cycle인 Al2O3층의 두께 변화에 따른 특성을 최적화하기 위해 공정 온도를 $250^{\circ}C$ 고정하고, 열처리 온도와 시간을 가변하였으며 유효 반송자수명을 측정하여 알루미늄 산화막의 패시베이션 특성을 확인했다.

• Journal of Electrochemical Science and Technology
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• 제10권4호
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• pp.424-432
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• 2019

Planar BiVO₄ and 3 wt% Mo-doped BiVO₄ (abbreviated as Mo:BiVO₄) film were prepared by the facile spin-coating method on fluorine doped SnO₂(FTO) substrate in the same precursor solution including the Mo precursor in Mo:BiVO₄ film. After annealing at a high temperature of 450℃ for 30 min to improve crystallinity, the films exhibited the monoclinic crystalline phase and nanoporous architecture. Both films showed no remarkably discrepancy in crystalline or morphological properties. To investigate the effect of surface passivation exploring the Al₂O₃ layer, the ultra-thin Al₂O₃ layer with a thickness of approximately 2 nm was deposited on BiVO₄ film using the atomic layer deposition (ALD) method. No distinct morphological modification was observed for all prepared BiVO₄ and Mo:BiVO₄ films. Only slightly reduced nanopores were observed. Although both samples showed some reduction of light absorption in the visible wavelength after coating of Al₂O₃ layer, the Al₂O₃ coated BiVO₄ (Al₂O₃/BiVO₄) film exhibited enhanced photoelectrochemical performance in 0.5 M Na₂SO₄ solution (pH 6.5), having higher photocurrent density (0.91 mA/㎠ at 1.23 V vs. reversible hydrogen electrode (RHE), briefly abbreviated as V_RHE) than BiVO₄ film (0.12 mA/㎠ at 1.23 V_RHE). Moreover, Al₂O₃ coating on the Mo:BiVO₄ film exhibited more enhanced photocurrent density (1.5 mA/㎠ at 1.23 V_RHE) than the Mo:BiVO₄ film (0.86 mA/㎠ at 1.23 V_RHE). To examine the reasons, capacitance measurement and Mott-Schottky analysis were conducted, revealing that the significant degradation of capacitance value was observed in both BiVO₄ film and Al₂O₃/Mo:BiVO₄ film, probably due to degraded capacitance by surface passivation. Furthermore, the flat-band potential (V_FB) was negatively shifted to about 200 mV while the electronic conductivities were enhanced by Al₂O₃ coating in both samples, contributing to the advancement of PEC performance by ultra-thin Al₂O₃ layer.