• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.209-209
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• 2012

High-efficient transparent conductive oxide (TCO) film-embedding Si heterojunction solar cells were fabricated. An additional doping was not applied for heterojunction solar cells due to the spontaneous junction formation between TCO films and an n-type Si substrate. Three different TCO coatings were formed by sputtering method for an Al-doped ZnO (AZO) film, an indium-tin-oxide (ITO) film and double stacks of ITO/AZO films. An improved crystalline ITO film was grown on an AZO template upon hetero-epitaxial growth. This double TCO films-embedding Si heterojunction solar cell provided significantly enhanced efficiency of 9.23% as compared to the single TCO/Si devices. The effective arrangement of TCO films (ITO/AZO) provides benefits of a lower front contact resistance and a smaller band offset to Si leading enhanced photovoltaic performances. This demonstrates a potential scheme of the effective TCO film-embedding heterojunction Si solar cells.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.239.2-239.2
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• 2016

Numerous studies and approaches have been performed for solar cells to improve their photoelectric conversion efficiencies. Among them, the study for electrode containing transparent conducting oxide (TCO) layers is one of issues as well as for the cell structure based on band theory. In this study, we focused on an interfacial layer between p-type silicon and indium tin oxide (ITO) well-known as TCO materials. According to current-voltage characteristics for the sample with the interfacial layers, the improvement of band alignment between p-type silicon and ITO was observed, and their ohmic properties were enhanced in the proper condition of deposition. To investigate cause of this improvement, spectroscopic ellipsometry and ultraviolet photoelectron spectroscopy were utilized. Using these techniques, band alignment and defect in the band gap were examined. The major materials of the interfacial layer are vanadium oxide and tungsten oxide, which are notable as a hole transfer layer in the organic solar cells. Finally, the interfacial layer was applied to silicon solar cells to see the actual behavior of carriers in the solar cells. In the case of vanadium oxide, we found 10% of improvement of photoelectric conversion efficiencies, compared to solar cells without interfacial layers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.10
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• pp.923-929
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• 2008

On the piezoelectric polymer, PVDF (poly vinylidene fluoride), the transparent conducting oxide (TCO) electrode material thin film was deposited by roll to roll sputtering process mentioned as a mass product-friendly process for display application. The deposition method for ITO Indium Tin Oxides) as our TCO was DC magnetron sputtering optimized for polymer substrate with the low process temperature. As a result, a high transparent and good conductive ITO/PVDF film was prepared. During the process, especially, the gas mixture ratio of Ar and Oxygen was concluded as an important factor for determining the film's physical properties. There were the optimum ranges for process conditions of mixture gas ratio for ITO/PVDF From these results, the doping mechanism between the oxygen atom and the metal element, Indium or Tin was highly influenced by oxygen partial pressure condition during the deposition process at ambient temperature, which gives the conductivity to oxide electrode, as generally accepted. With our studies, the process windows of TCO for display and other application can be expected.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.324-324
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• 2012

투명전도체(Transparent Conducting Oxides: TCOs)는 일반적으로 면저항이 $103{\Omega}/sq$ 이하로 전기가 잘 통하며, 가시광선영역인 380~780 nm에서의 투과율이 80% 이상이고, 3.2eV 이상의 밴드갭을 가지는 재료로써, 전기전도도와 가시광선영역에서 투과성이 높아 전기적, 광학적 재료로 관심을 받아 다년간 연구대상이 되어오고 있다. 현재 가장 널리 사용되고 있는 투명전도체(Transparent Conducting Oxides: TCOs) 소재로는 Indium Tin Oxide (ITO)가 가장 각광받고 있지만, Indium의 가격상승과 박막의 열처리를 통해 저항이 증가하는 단점을 가지고 있어 이를 대체 할 새로운 소재 개발이 필요한 상황이다. 그러므로 투명전도체 소재 개발에 있어서 가장 중요한 연구과제는 Indium Tin Oxide(ITO)의 단점을 개선시키고 안정된 고농도의 In-Zn-Sn-O(ITZO) 박막을 성장시키는 것이다. 본 연구에서는 RF스퍼터링법에 의하여 Si wafer에 In-Zn-Sn-O(IZTO)를 $350{\AA}$ 만큼 증착시키고, 1시간 동안 $300^{\circ}C$, $350^{\circ}C$, $400^{\circ}C$로 각각 열처리 하였다. 박막의 전자적, 광학적 특성은 XPS(X-ray Photoelectron Spectroscopy), REELS(Reflection Electron Energy Loss Spectroscopy)를 이용하여 연구하였다. XPS측정결과, ITZO박막은 In-O, Sn-O and Zn-O의 결합을 가지고 있고, 박막의 열처리를 통해 $400^{\circ}C$에서 Zn2p의 피크가 가장 크게 나타나는 반면 In3d와 Sn3d는 열처리를 했을 때가 Room Temperature에서 보다 피크가 작아지는 것을 확인하였다. 이는 $400^{\circ}C$에서 Zn가 표면에 편석됨을 나타낸다. 그리고 REELS를 이용해 Ep=1500 eV에서의 밴드갭을 얻어보면, 밴드갭은 $3.25{\pm}0.05eV$로 온도에 크게 변화하지 않았다. 또한 QUEELS -Simulation에 의한 광학적 특성 분석 결과, 가시광선영역인 380nm~780nm에서의 투과율이 83%이상으로 투명전자소자로의 응용이 가능하다는 것을 보여주었다.

• Journal of the Korean Vacuum Society
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• v.7 no.1
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• pp.43-50
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• 1998

Transparent and conducting tin oxide films were prepared on Pyrex glass substrates by the remote plasma chemical vapor deposition (RPCVD). The main control variables of the RPCVD process included the deposition time, the flow rates of tetramethyltin, oxygen and argon, the radio-frequency power, and the substrate temperature. Dependence of the deposition rate, electric resistivity, optical transmittance and crystal structure on these parameters was systematically examined to prepare high qualities of tin oxide films and to better understand RPCVD process. The effect of those parameters on the properties of tin oxide films in complicatedly related on another. A tin oxide film parameters on the protimized deposition conditions exhibited deposition rate of 102 $\AA$/min, electric resistivity of $9.7\times 10^{-3}\Omega$cm and visible transmittance of ~80%.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.314.1-314.1
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• 2013

Transparent conducting nanoscale-domes were periodically patterned on a Si substrate by nanoimprint method. Transparent conductor of indium-tin-oxide (ITO) was shaped as a nanodome, which effectively drives the incident light effectively into a light-absorber and therefore induces a substantially enhanced photo-response. An ITO nanodome is electrically isolated from the neighboring nanodomes. This structure benefits to provide a low contact between a Si substrate and a front metal electrode giving an efficient electrical path. The ITO nanodome device showed a significantly enhanced photo-response of 6010 from the value of 72.9 of a planar ITO film. The electrical and optical advantage of an ITO nanodome is suitable for various photoelectric applications.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.9
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• pp.798-801
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• 2007

Multilayer transparent electrodes, having a much lower electrical resistance than the widely used transparent conducting oxide electrodes, were prepared by using radio frequency magnetron sputtering. The multilayer structure consisted of five layers, indium tin oxided (ITO)/zinc oxide (ZnO)/Ag/zinc oxide (ZnO)/ITO. With about 50 nm thick ITO films, the multilayer showed a high optical transmittance in the visible range of the spectrum and had color neutrality. The electrical and optical properties of ITO/ZnO/Ag/ZnO/ITO multilayer were changed mainly by Ag film properties, which were affected by the deposition process of the upper layer. Especially ZnO layer was improved to adhesion of Ag and ITO. A high quality transparent electrode, having a resistance as low as and a high optical transmittance of 91% at 550 nm, was obtained. It could satisfy the requirement for the flexible OLED and LCD.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.397-397
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• 2007

Multilayer transparent electrodes, having a much lower electrical resistance than the widely used transparent conducting oxide electrodes, were prepared by using radio frequency magnetron sputtering. The multilayer structure consisted of five layers, indium tin oxided(ITO)/zinc oxide(ZnO)/Ag/oxide(ZnO)/ITO. With about 50nm thick ITO films, the multilayer showed a high optical transmittance in the visible range of the spectrum and had color neutrality. The electrical and optical properties of ITO/ZnO/Ag/ZnO/ITO multilayer were changed mainly by Ag film properties, which were affected by the deposition process of the upper layer. Especially ZnO layer was improved to adhesion of Ag and ITO. A high quality transparent electrode, having a resistance as low as and a high optical transmittance of 91% at 550nm, was obtained. It could satisfy the requirement for the flexible OLED and LCD.

• Journal of Electrochemical Science and Technology
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• v.3 no.2
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• pp.68-71
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• 2012

The electrospinning technique is a revolutionary template-catalyst-free method that can generate 1D nanostructure with the tunability and the potential for the mass production. This approach received a great deal of attention due to its ability to give direct pathways for electrical current and has been utilized in various electronic applications. However, the delamination of inorganic electrospun film has prevented the intense utilization due to the thermal expansion/contraction during the calcination. In this study, we propose an electrical grounding method for transparent conducting oxide and electrospun nanowires to enhance the adhesion after the calcination. Then, we examined the potential of the technique on ZnO based dye-sensitized solar cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.4
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• pp.282-285
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• 2012

It is well known that Zinc Oxide (ZnO) is an attractive material for its various applications. ZnO has been mostly used as a transparent conducting oxide in liquid crystal displays, solar cells due to its advantages of low cost, high productivity, and excellent electrical conductivity. Notably, flexible-dye-sensitized solar cells (DSSCs) based on polyethylene terephthalate (PET) substrates require low temperature sintering processing conditions. Therefore, low temperature processing conditions have been strongly required for transparent conducting film applications. In this paper, we prepared low temperature-sintered ZnO ceramics employing Li as a sintering aid.