• Korean Journal of Materials Research
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• v.33 no.11
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• pp.475-481
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• 2023

Recently, the electron transport layer (ETL) has become one of the key components for high-performance perovskite solar cell (PSC). This study is motivated by the nonreproducible performance of ETL made of spin coated SnO₂ applied to a PSC. We made a comparative study between tin oxide deposited by atomic layer deposition (ALD) or spin coating to be used as an ETL in N-I-P PSC. 15 nm-thick Tin oxide thin films were deposited by ALD using tetrakisdimethylanmiotin (TDMASn) and using reactant ozone at 120 ℃. PSC using ALD SnO₂ as ETL showed a maximum efficiency of 18.97 %, and PSC using spin coated SnO₂ showed a maximum efficiency of 18.46 %. This is because the short circuit current (Jsc) of PSC using the ALD SnO₂ layer was 0.75 mA/cm² higher than that of the spin coated SnO₂. This result can be attributed to the fact that the electron transfer distance from the perovskite is constant due to the thickness uniformity of ALD SnO₂. Therefore ALD SnO₂ is a candidate as a ETL for use in PSC vacuum deposition.

• The Journal of the Convergence on Culture Technology
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• v.4 no.3
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• pp.287-291
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• 2018

The CNTFET, which is attracting attention as a next-generation semiconductor device, can obtain ballistic or near-ballistic transport at a lower voltage than that of conventional MOSFETs by depositing CNTs between the source and drain of the device. In order to increase the performance of the CNTFET, a large number of CNTs must be deposited at a high density in the CNTFET. Thus, various manufacturing processes to increase the density of the CNTs have been developed. Recently, the Directional Shrinking Transfer Method was developed and showed that the current density of the CNTFET device could be increased up to 150 uA/um. So, this method enhances the possibility of implementing a CNTFET-based integrated circuit. In this paper, we will discuss how to evaluate the performance of the CNTFET device compared to a MOSFET at the circuit level when the CNTFET is fabricated by the Directional Shrinkage Transfer Method.

• Korean Journal of Materials Research
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• v.28 no.1
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• pp.32-37
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• 2018

We report on the efficient detection of NO gas by an all-oxide semiconductor p-n heterojunction diode structure comprised of n-type zinc oxide (ZnO) nanorods embedded in p-type copper oxide (CuO) thin film. The CuO thin film/ZnO nanorod heterostructure was fabricated by directly sputtering CuO thin film onto a vertically aligned ZnO nanorod array synthesized via a hydrothemal method. The transport behavior and NO gas sensing properties of the fabricated CuO thin film/ZnO nanorod heterostructure were charcterized and revealed that the oxide semiconductor heterojunction exhibited a definite rectifying diode-like behavior at various temperatures ranging from room temperature to $250^{\circ}C$. The NO gas sensing experiment indicated that the CuO thin film/ZnO nanorod heterostructure had a good sensing performance for the efficient detection of NO gas in the range of 2-14 ppm under the conditions of an applied bias of 2 V and a comparatively low operating temperature of $150^{\circ}C$. The NO gas sensing process in the CuO/ZnO p-n heterostructure is discussed in terms of the electronic band structure.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.26-30
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• 2001

In this paper, transient characteristics of IGBT has been analytically solved to express the excess minority carrier distribution in active base region and the output voltage. Non-Punch Through(NPT) structure has been selected to prove the validity of the model. It is based on the equivalent circuit of MOSFET which supplies a low gain and a high level injection to the base of BJT. None of the quasi static conditions have been assumed to trace the transient characteristics. The basic elements of the model have been derived from the ambipolar transport theory. Theoretical predictions of the output voltages have been obtained with different lifetimes and compared with experimental and theoretical results available in the literature. From the analytical approach, good agreement has been obtained to provide reliable and fast output of the device.

• Electronics and Telecommunications Trends
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• v.28 no.6
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• pp.49-62
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• 2013

광-회선-패킷 통합 전달망 장비는 광전송망, 회선 망, 패킷 전달망 계층을 하나로 통합한 장비로써, 패킷-회선 교환 전달, ROADM(Reconfigurable Optical Add/Drop Multiplexer) 광파장 교환 전달, GMPLS(Generalized Multi-Protocol Label Switching) 기반 통합제어 및 관리기능을 수행하면서 네트워크 구조의 단순화, 네트워크 제어의 지능화, 그리고 네트워크 용량의 광대역화를 구현한다. 트래픽 폭증과 전송용량 부족 현상을 해결하고, 트래픽 증가 대비 수익의 탈동조화 현상을 극복하기 위해 네트워크 CAPEX(Capital Expenditures)/OPEX(Operating Expenditures)를 절감함으로써 통신사업자의 투자 여건을 우호적으로 조성하면서 최근 주목 받고 있는 기술이다. 본고에서는 광-회선-패킷 통합 전달망의 기술동향을 기술한 것으로써, 배경, 필요성 및 개념 개발동향 및 경쟁기술에 대해서 살펴보고, 기술발전 로드랩 및 주요 기술 동향과 시장 및 사업화 전망에 대해서 분석한다.

• New & Renewable Energy
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• v.3 no.3
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• pp.14-19
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• 2007

A flow channel model of a bipolar plate with varying cross-sectional area was newly designed for improving performance and efficiency of a PEM fuel cell stack. As a result, the varying cross-sectional area model showed poor uniformity in velocity distribution, however, maximum velocity in the flow path is about 30% faster than that of the uniform cross-sectional area model. The proposed varying cross-sectional area model is expected to diffuse operating fluids more easily into diffusion layer because it has relatively higher values in pressure distribution compared with other flow channel models. It is expected that the implementation of the varying cross-sectional area model can reduce not only the mass transport loss but also the activation loss in a PEM fuel cell, and open circuit voltage of a fuel cell can thus be increased slightly.

• Journal of computational fluids engineering
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• v.3 no.2
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• pp.27-38
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• 1998

Rotating flow of a stratified fluid contained in a circular cylinder with unstable temperature gradient imposed on the side wall of it has been numerically studied. The temperatures at the endwall disks are constant. The top disk of the container is coider than that of the bottob disk, as much as the temperature difference n${\Delta}$T, (0${\leq}$n${\leq}$3). Flows in the vessel are driven by an impulsive rotation of the hot bottom disk with respect to the central axis of the cylinder. Flow details have been acquired. For this flow, the principal balance in the interior core is characterized by a relationship between the radial temperature gradient and the vertical shear in the azimuthal velocity. As the buoyancy effect becomes appreciable, larger portions of the meridional fluid transport are long-circuit from the bottom disk to the interior region via the side wall.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.47-48
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• 2005

The moving photocarrier grating(MPG) technique for the determination of the carrier mobilities and the recombination lifetime in a-Se:As films have been studied. The electron and hole drift mobility and the recombination lifetime of a-Se films with arsenic (As) additions have been obtained. We have found an increase in hole drift mobility and recombination lifetime, especially when 0.3% As is added into a-Se film. However, the electron mobility exhibits no observable change up to 0.5% As addition in a-Se films.0.3% As added a-Se film also exhibits the maximum short circuit current densities per laser intensity of $5.29\times10^{-7}$ A/W.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.72-72
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• 2011

Surface science is intrinsically related to the performance of solar cells. In solar cells the generation and collection of charge carriers determines their efficiency. Effective transport of charge carriers across interfaces and minimization of their recombination at surfaces and interfaces is of utmost importance. Thus, the chemistry at the surfaces and interfaces of these devices must be determined, and related to their performance. In this talk we will discuss the role of two important interfaces, First, the role of surface passivation is very important in limiting the rate of carrier of recombination. Here we will combine x-ray photoelectron spectroscopy of the surface of a Si device with electrical measurements to ascertain what factors determine the quality of a solar cell passivation. In addition, the quality of the heterojunction interface in a ZnSe/CdTe solar cell affects the output voltage of this device. X-ray photoelectron spectroscopy gives some insight into the composition of the interface, while ultraviolet photoemission yields the relative energy of the two materials' valence bands at the junction, which controls the open circuit voltage of the solar cell. The relative energies of ZnSe and CdTe at the interface is directly affected by the material quality of the interface through processing.

• Transactions on Electrical and Electronic Materials
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• v.6 no.6
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• pp.280-283
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• 2005

The moving photocarrier grating (MPG) technique for the determination of the carrier mobilities and the recombination lifetime of $\alpha$-Se:As films has been studied. The electron and hole drift mobility and the recombination lifetime of $\alpha$-Se films with arsenic (As) additions have been obtained from measurement of the short circuit current density $j_{sc}$ as a function of grating velocity and spatial period. The hole mobility decreases due to defect density of hole traps when x exceeds 0.003, whereas the hole mobility increases for the case of low As addition (x$\le$0.003). We have found an increase in hole drift mobility and recombination lifetime, especially when As with (x = 0.003) is added into the $\alpha$-Se film.