• ETRI Journal
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• 제35권4호
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• pp.730-733
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• 2013

In this work, buffer layers with various conditions are inserted at an n/i interface in hydrogenated amorphous silicon semitransparent solar cells. It is observed that the performance of a solar cell strongly depends on the arrangement and thickness of the buffer layer. When arranging buffer layers with various bandgaps in ascending order from the intrinsic layer to the n layer, a relatively high open circuit voltage and short circuit current are observed. In addition, the fill factors are improved, owing to an enhanced shunt resistance under every instance of the introduced n/i buffer layers. Among the various conditions during the arrangement of the buffer layers, a reverse V shape of the energy bandgap is found to be the most effective for high efficiency, which also exhibits intermediate transmittance among all samples. This is an inspiring result, enabling an independent control of the conversion efficiency and transmittance.

• 한국결정성장학회지
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• 제23권4호
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• pp.161-166
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• 2013

실리콘 기판 위에 GaN를 성장하기 위해서 AlN 완충층을 사용해 왔다. 그러나 AlN은 아직까지 high doping이 쉽지 않기 때문에, 이로 인해 AlN를 전자소자나 광소자 제작을 위한 완충층으로 이용하는 경우 직렬 저항의 증가라는 문제가 발생할 수 있다. 본 연구에서는 이러한 문제점을 개선하기 위해 AlN 완충층 대신에 금속 완충층을 사용하여 실리콘 기판 위에 GaN 박막 성장실험을 수행하였다. Al, Ti, Cr 그리고 Au 등을 금속 완충층으로 사용하여 실리콘 기판 위에 GaN 층을 성장하였다. 성장된 GaN 박막의 표면 특성을 분석하기 위해 광학현미경과 SEM을 사용하였고, 결정성과 광학적 특성을 평가하기 위하여 PL과 XRD 분석을 실시하였으며 AlN 완충층을 사용한 경우와 금속 완충층을 사용한 경우의 저항 차이를 확인하기 위하여 전류-전압 특성을 측정하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 센서 박막재료 반도체재료 기술교육
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• pp.82-85
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• 2002

In recent years, the tantalum nitride(TaN) thin-film has been developed for the electronic resistor and capacitor. In this papers, this study presents the surface profile and sheet-resistance property relationship of reactive-sputtered TaN thin film resistor processed by buffer of Ti and Cr on alumina substrate. The TCR properties of the TaN films were discussed in terms of reactive gas ratio, ratio of nitrogen, crystallization and thin films surface morphology due to annealing temperature. It is clear that the TaN thin-films resistor electrical properties are low TCR related with it's buffer layer condition. Ti buffer layer thin film resistor having a good thermal stability and lower TCR properties then Cr buffer expected for the application to the dielectric material of passive component.

• Journal of Ceramic Processing Research
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• 제13권spc2호
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• pp.336-340
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• 2012

Wide band gap p-type hydrogenated amorphous silicon oxide (a-SiO:H) buffer layer has been used at the interface of transparent conductive oxide (TCO) and hydrogenated amorphous silicon (a-Si:H) p-type layer of a p-i-n type a-Si:H solar cell. Introduction of 5 nm thick buffer layer improves in blue response of the cell along with 0.5% enhancement of photovoltaic conversion efficiency (η). The cells with buffer layer show higher open circuit voltage (Voc), fill factor (FF), short circuit current density (Jsc) and improved blue response with respect to the cell without buffer layer.

• Transactions on Electrical and Electronic Materials
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• 제10권1호
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• pp.24-27
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• 2009

N-doped ZnO thin films were deposited on n-type Si(100) and homo-buffer layer, and undoped ZnO thin film was also deposited on homo-buffer layer by RF magnetron sputtering method. After deposition, all films were in-situ annealed at $800^{\circ}C$ for 5 minutes in ambient of $O_2$ with pressure of 10Torr. X -ray diffraction shows that the homo-buffer layer is beneficial to the crystalline of N-doped ZnO thin films and all films have preferable c-axis orientation. Atomic force microscopy shows that undoped ZnO thin film grown on homo-buffer layer has an evident improvement of smoothness compared with N-dope ZnO thin films. Hall-effect measurements show that all ZnO films annealed at $800^{\circ}C$ possess p-type conductivities. The undoped ZnO film has the highest carrier concentration of $1.145{\times}10^{17}cm{-3}$. The photoluminescence spectra show the emissions related to FE, DAP and many defects such as $V_{Zn}$, $Zn_O$, $O_i$ and $O_{Zn}$. The p-type defects ($O_i$, $V_{Zn}$, and $O_{Zn}$) are dominant. The undoped ZnO thin film has a better p-type conductivity compared with N-doped ZnO thin film.

• 한국재료학회지
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• 제21권1호
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• pp.34-38
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• 2011

In this study, the effects of an annealed buffer layer with different thickness on heterojunction diodes based on the ZnO/ZnO/p-Si(111) systems were reported. The effects of an annealed buffer layer with different thickness on the structural, optical, and electrical properties of zinc oxide (ZnO) films on p-Si(111) were also studied. Before zinc oxide (ZnO) deposition, different thicknesses of ZnO buffer layer, 10 nm, 30 nm, 50 nm and 70 nm, were grown on p-Si(111) substrates using a radio-frequency sputtering system; samples were subsequently annealed at $700^{\circ}C$ for 10 minutes in $N_2$ in a horizontal thermal furnace. Zinc oxide (ZnO) films with a width of 280nm were also deposited using a radio-frequency sputtering system on the annealed ZnO/p-Si (111) substrates at room temperature; samples were subsequently annealed at $700^{\circ}C$ for 30 minutes in $N_2$. In this experiment, the structural and optical properties of ZnO thin films were studied by XRD (X-ray diffraction), and room temperature PL (photoluminescence) measurements, respectively. Current-voltage (I-V) characteristics were measured with a semiconductor parameter analyzer. The thermal tensile stress was found to decrease with increasing buffer layer thickness. Among the ZnO/ZnO/p-Si(111) diodes fabricated in this study, the sample that was formed with the condition of a 50 nm thick ZnO buffer layer showed a strong c-axis preferred orientation and I-V characteristics suitable for a heterojunction diode.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.60-60
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• 2009

기존의 박막 실리콘 태양전지는 TCO와 p-layer 사이의 Bandgap차이가 p-layer, i-layer, n-layer 사이의 Bandgap 차이보다 커서 TCO를 통과한 태양광이 p-layer에 흡수되기 전에 일정량 손실된다. 이를 해결하기 위하여, p-layer 위에 기존의 p-layer보다 높은 Bandgap을 갖는 p buffer layer가 추가된 박막 실리콘 태양전지 구조를 만들어서 흡수되는 태양광의 손실량을 줄이고, 변환효율을 높이고자 하였다. 실험은 ASA Simulator를 이용하여 진행하였으며, Simulation결과 1.92eV의 Bandgap을 갖는 p buffer layer의 추가로 인하여, 기존 10.64%에서 11.16%로 증가된 변환효율을 얻을 수 있었다. Bandgap뿐만 아니라 다른 요소의 최적화도 이루어진다면, 기존의 박막 실리콘 태양전지보다 훨씬 높은 변환효율을 갖는 박막 실리콘 태양전지를 설계 하는 것이 가능 할 것이다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1998년도 추계학술발표강연 및 논문개요집
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• pp.98-98
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• 1998

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1277-1279
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• 1994

In the structure of ZnO/nip-SiC: H/metal substrate amorphous silicon (a-Si:H) solar cells, the effects of inserting a rear textured ZnO in the p-SiC:H/metal interface and a graded bandgap buffer layer in the i/p-SiC:H have been analysed by computer simulation. The incident light was taken to have an intensity of $100mW/cm^2$(AM-1). The thickness of the a-Si:H n, ${\delta}$-doped a-SiC:H p, and buffer layers was assumed to be $200{\AA},\;66{\AA}$, and $80{\AA}$, respectively. The scattering coefficients of the front and back ZnO were taken to be 0.2 and 0.7, respectively. Inserting the rear buffer layer significantly increases the open circuit voltage($V_{oc}$) due to reduction of the i/p interface recombination rate. The use of textured ZnO markedly improves collection efficiency in the long wavelengths( above ${\sim}550nm$ ) by back scattering and light confinement effects, resulting in dramatic enhancement of the short circuit current density($J_{sc}$). By using the rear buffer and textured ZnO, the i-layer thickness of the ceil for obtaining the maximum efficiency becomes thinner(${\sim}2500{\AA}$). From these results, it is concluded that the use of textured ZnO and buffer layer at the backside of the ceil is very effective for enhancing the conversion efficiency and reducing the degradation of a-Si:H pin-type solar cells.

• 한국결정성장학회지
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• 제19권4호
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• pp.159-164
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• 2009

실리콘 기판에 GaN 에피성장을 확인하기 위해, P형 Si(100), Si(111) 기판 전면에 버퍼층으로 40 nm 두께의 코발트실리사이드를 형성시켰다. 형성된 코발트실리사이드 층에 연속으로 HVPE(hydride vapor phase epitaxy)로 하나는 $850^{\circ}C$-12분 + $1080^{\circ}C$-30분(공정I)과, 또 하나 조건은 $557^{\circ}C$-5분 + $900^{\circ}C$-5분(공정II) 조건으로 각각 나누어 진행하여 보았다. GaN의 에피성장을 광학현미경, 주사전자현미경, 주사탐침현미경, 그리고 HR-XRD로 확인하였다. 공정I로는 GaN의 에피성장이 진행되지 않았으며, 공정II에서는 에피성장이 진행되었다. 특히 공정 II는 열팽창에 의해 실리콘 기판과의 자가정렬적인 기판분리 현상을 보였으며, XRD로 GaN의 0002 방향의 결정성 (crystallinity)을 ${\omega}$-scan으로 확인한 결과(100)면 방향의\ 실리콘과 코발트실리사이드를 버퍼층으로 활용하고 저온에서 HVPE를 진행한 조합이 GaN의 에피성장에 유리하였다.