• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.29-32
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• 2001

Hydrogen passivation of Si nanocrystals identifies luminescence mechanism indirectly. Si nanocrystallites thin films on p-type (100) Si substrate have been fabricated by pulsed laser deposition technique using a Nd:YAG laser After deposition, Si nanocrystallites thin films have been annealed at 600$^{\circ}C$ and 760$^{\circ}C$ in nitrogen ambient, respectively. Hydrogen passivation was subsequently performed at 500$^{\circ}C$ in forming gas (95 % N$_2$ + 5 % H$_2$) for an 1 hour. We report the photoluminescnece(PL) property of Si thin films by the hydrogen passivation. The luminescence mechanism of Si nanocrystallites has also been investigated.

• Corrosion Science and Technology
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• v.9 no.1
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• pp.20-28
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• 2010

According to the bipolar model, ion selectivity of some species in the passive film is important factor to control the passivation. An increase of cation selectivity of outer layer of the passive film can stabilize the film and improves the corrosion resistance. Therefore, the formation and roles of ionic species in the passive film should be elucidated. In this work, two types of solution (hydrochloric or sulfuric acid) were used to test high N and Mo-bearing stainless steels. The objective of this work was to investigate the formation of oxyanions in the passive film and the roles of oxyanions in passivation of stainless steel. Nitrogen exists as atomic nitrogen, nitric oxide, nitro-oxyanions (${NO_x}^-$), and N-H species, not nitride in the passive film. Because of its high mobility, the enriched atomic nitrogen can act as a reservoir. The formation of N-H species buffers the film pH and facilitates the formation of oxyanions in the film. ${NO_x}^-$ species improve the cation selectivity of the film, increasing the oxide content and film density. ${NO_x}^-$ acts similar to a strong inhibitor both in the passive film and at active sites. This facilitates the formation of chromium oxide. Also, ${NO_x}^-$ can make more molybdate and nitric oxide by reacting with Mo. The role of Mo addition on the passivation characteristics of stainless steel may differ with the test environment. Mo exists as metallic molybdenum, molybdenum oxide, and molybdate and the latter facilitates the oxide formation. When nitrogen and molybdenum coexist in stainless steel, corrosion resistance in chloride solutions is drastically increased. This synergistic effect of N and Mo in a chloride solution is mainly due to the formation of nitro-oxyanions and molybdate ion. Oxyanions can be formed by a 'solid state reaction' in the passive film, resulting in the formation of more molybdate and nitric oxide. These oxyanions improve the cation selectivity of the outer layer and form more oxide and increase the amount of chromium oxide and the ratio of $Cr_2O_3/Cr(OH)_3$ and make the film stable and dense.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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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.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.75-81
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• 2018

The effect of $Ar-N_2$ plasma treatment on Cu surface as one of solutions to realize reliable Cu-Cu wafer bonding was investigated. Structural characteristic of $Ar-N_2$ plasma treated Cu surface were analyzed using X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscope. Ar gas was used for a plasma ignition and to activate Cu surface by ion bombardment, and $N_2$ gas was used to protect the Cu surface from contamination such as -O or -OH by forming a passivation layer. The Cu specimen under high Ar partial pressure plasma treatment showed more copper oxide due to the activation on Cu surface, while Cu surface after high $N_2$ gas partial pressure plasma treatment showed less copper oxide due to the formation of Cu-N or Cu-O-N passivation layer. It was confirmed that nitrogen plasma can prohibit Cu-O formation on Cu surface, but nitrogen partial pressure in the $Ar-N_2$ plasma should be optimized for the formation of nitrogen passivation layer on the entire surface of Cu wafer.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.6
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• pp.236-239
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• 2002

Si nanocrystallites thin films on P-type (100) Si substrate have been fabricated by pulsed laser deposition using a Nd:YAG laser. After deposition, samples were annealed in several environmental gases ;It the temperature range of 400 to $800^{\circ}C$ Hydrogen passivation was then performed in the forming gas (95 % $N_2$ + 5 % $H_2$) for 1 hr. Strong violet-indigo photoluminescence has been observed at room temperature on nitrogen ambient-annealed Si nanocrystallites. We report the variation of photoluminescence (PL) properties of Si thin films by changing annealing temperatures and by using hydrogen passivation. The results could suggest that the origin of violet-indigo PL should be related to the Quantum size effect of Si nanocrystallite.

• Korean Journal of Materials Research
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• v.19 no.1
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• pp.37-43
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• 2009

Silicon dioxide as gate dielectrics was grown at $400^{\circ}C$ on a polycrystalline Si substrate by inductively coupled plasma oxidation using a mixture of $O_2$ and $N_2O$ to improve the performance of polycrystalline Si thin film transistors. In conventional high-temperature $N_2O$ annealing, nitrogen can be supplied to the $Si/SiO_2$ interface because a NO molecule can diffuse through the oxide. However, it was found that nitrogen cannot be supplied to the Si/$SiO_2$ interface by plasma oxidation as the $N_2O$ molecule is broken in the plasma and because a dense Si-N bond is formed at the $SiO_2$ surface, preventing further diffusion of nitrogen into the oxide. Nitrogen was added to the $Si/SiO_2$ interface by the plasma oxidation of mixtures of $O_2/N_2O$ gas, leading to an enhancement of the field effect mobility of polycrystalline Si TFTs due to the reduction in the number of trap densities at the interface and at the Si grain boundaries due to nitrogen passivation.

• Current Photovoltaic Research
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• v.11 no.3
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• pp.87-95
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• 2023

As the demand for the Internet of Things grows, research into indoor photovoltaics for wireless power is becoming important. In particular, perovskite has attracted considerable attention due to its superior performance compared to other candidates. However, various surface defects present in perovskite are a limiting factor for high performance. In particular, deep-level surface defects caused by uncoordinated Pb²⁺ ions directly limit charge transport. In low light environments, this appears to be a more significant hurdle. In this study, ethylenediamine, which can provide covalent bonding to uncoordinated Pb²⁺ ions through nitrogen, was used as a surface treatment material for indoor photovoltaics. X-ray photoelectron spectroscopy confirmed that the uncoordinated Pb²⁺ ions were effectively passivated by the terminal nitrogen of ethylenediamine. As a consequence, a V_OC of 0.998 V, a JSC of 0.139 mA cm^-2 and a fill factor of 83.03% were achieved, resulting in an indoor photoelectric conversion efficiency of 38.02%.

• Korean Journal of Materials Research
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• v.12 no.9
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• pp.724-728
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• 2002

Inductively-coupled $N_2$O plasma was utilized to grow silicon dioxide at low temperature and applied to fabricate polycrystalline-silicon thin film transistors. At $400^{\circ}C$, the thickness of oxide was limited to 5nm and the oxide contained Si≡N and ≡Si-N-Si≡ bonds. The nitrogen incorporation improved breakdown field to 10MV/cm and reduced the interface charge density to $1.52$\times$10^{11}$ $cm^2$ with negative charge. The $N_2$O plasma gate oxide enhanced the field effect mobility of polycrystalline thin film transistor, compared to $O_2$ plasma gate oxide, due to the reduced interface charge at the $Si/SiO_2$ interface and also due to the reduced trap density at Si grain boundaries by nitrogen passivation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.4
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• pp.334-338
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• 2006

Poly silicon TFT requires high quality dielectric film; conventional method of growing silicon dioxide needs highly hazardous chemicals such as silane. We have grown high quality dielectric film of silicon dioxide using non-hazardous chemical such as TFOS and ozone as reaction gases by APCVD. The films grown were characterized through C-V curves of MOS structures. Conventional APCVD requires high temperature processing where as in the process of current study, we developed a low temperature process. Interface trap density was substantially decreased in the silicon surface coated with the silicon dioxide film after annealing in nitrogen ambient. The interface with such low trap density could be used for poly silicon TFT fabrication with cheaper cost and potentially less hazards.