• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.95-95
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• 2009

실리콘 이종접합 태양전지는 비정질 실리콘을 사용하여 p-n 접합을 만들기 때문에 결정질 태양전지에 비해 개방전압이 높은 특성을 보인다. 그렇지만 결정질 태양전지는 접합을 확산공정으로 만들어 p층과 n층의 계면에서 결함이 존재하지 않는 반면 이종접합 태양전지는 결정질 실리콘 표면에 접합을 만들기 때문에 결정질 실리콘의 표면에 defect이 존재할 가능성이 많아진다. 이번 실험에서 결정질 실리콘의 cleaning 조건 변화에 따른 이종접합 태양전지의 특성변화를 보았다. 실리콘 이종접합 태양전지는 전면전극/ITO/p a-Si:H/i a-Si:H/n c-Si/i a-Si:H/n a-Si:H/후면전극의 구조로 만들으며 p형 및 n형 비정질 실리콘은 PECVD를 이용하여 증착하였고 i형 비정질 실리콘은 HWCVD를 이용하여 증착하였다. 만들어진 태양전지의 특성을 평가하기 위해 암전류 특성, 광전류 특성, 양자효율, 소수반송자수명을 측정하였다.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1654-1659
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• 2014

Tunneling field-effect transistors (TFETs) are very applicable to low standby-power application by their virtues of low off-current ($I_{off}$) and small subthreshold swing (S). However, low on-current ($I_{on}$) of silicon-based TFETs has been pointed out as a drawback. To improve $I_{on}$ of TFET, a gate-all-around (GAA) TFET based on III-V compound semiconductor with InAs/InGaAs/InP multiple-heterojunction structure is proposed and investigated. Its performances have been evaluated with the gallium (Ga) composition (x) for $In_{1-x}Ga_xAs$ in the channel region. According to the simulation results for $I_{on}$, $I_{off}$, S, and on/off current ratio ($I_{on}/I_{off}$), the device adopting $In_{0.53}Ga_{0.47}As$ channel showed the optimum direct-current (DC) performance, as a result of controlling the Ga fraction. By introducing an n-type InGaAs thin layer near the source end, improved DC characteristics and radio-frequency (RF) performances were obtained due to boosted band-to-band (BTB) tunneling efficiency.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.351.2-351.2
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• 2014

Indium tin oxide (ITO) has a lot of variations of its properties because it is basically in an amorphous state. Therefore, the differences in composition ratio of ITO can result in alteration of electrical properties. Normally, ITO is considered as transparent conductive oxide (TCO), possessing excellent properties for the optical and electrical devices. Quantitatively, TCO has transparency over 80 percent within the range of 380nm to 780nm, which is visible light although its specific resistance is less than $10-3{\Omega}/cm$. Thus, the solar cell is the best example for which ITO has perfectly matching profile. In addition, when ITO is used as transparent conductive electrode, this material essentially has to have a proper work function with contact materials. For instance, heterojunction with intrinsic thin layer (HIT) solar cell could have both front ITO and backside ITO. Because each side of ITO films has different type of contact materials, p-type amorphous silicon and n-type amorphous silicon, work function of ITO has to be modified to transport carrier with low built-in potential and Schottky barrier, and approximately requires variation from 3 eV to 5 eV. In this study, we examine the change of work function for different sputtering conditions using ultraviolet photoelectron spectroscopy (UPS). Structure of ITO films was investigated by spectroscopic ellipsometry (SE) and scanning electron microscopy (SEM). Optical transmittance of the films was evaluated by using an ultraviolet-visible (UV-Vis) spectrophotometer

• Korean Journal of Materials Research
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• v.20 no.4
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• pp.210-216
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• 2010

This paper investigates the dependence of a-Si:H/c-Si passivation and heterojunction solar cell performances on various cleaning processes of silicon wafers. It is observed that the passivation quality of a-Si:H thin-films on c-Si wafers depends highly on the initial H-termination properties of the wafer surface. The effective minority carrier lifetime (MCLT) of highly H-terminated wafer is beneficial for obtaining high quality passivation of a-Si:H/c-Si. The wafers passivated by p(n)-doped a-Si:H layers have low MCLT regardless of the initial H-termination quality. On the other hand, the MCLT of wafers incorporating intrinsic (i) a-Si:H as a passivation layer shows sensitive variation with initial cleaning and H-termination schemes. By applying the improved cleaning processes, we can obtain an MCLT of $100{\mu}sec$ after H-termination and above $600{\mu}sec$ after i a-Si:H thin film deposition. By adapting improved cleaning processes and by improving passivation and doped layers, we can fabricate a-Si:H/c-Si heterojunction solar cells with an active area conversion efficiency of 18.42%, which cells have an open circuit voltage of 0.670V, short circuit current of $37.31\;mA/cm^2$ and fill factor of 0.7374. These cells show more than 20% pseudo efficiency measured by Suns-$V_{oc}$ with an elimination of series resistance.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.113-116
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• 2005

In this paper, silicon thin-film solar cells(Si- TFSC) and a-Si/c-Si heterojunction solar cells(HJ-cell) are investigated. The Si-TFSC was prepared on glass substrate by depositing $1-3{\mu}m$ thin-film silicons by glow discharge method. The $a-Si:H/{\mu}c-Si:H$ tandem solar cells on textured ZnO:A1 TCO (transparent conducting oxide) showed improved Jsc in top and bottom cells than that on $SnO_2:F$ TCO. This enhancement of jsc resulted from improved light trapping effect by front textured ZnO:A1. The a-Si/c-Si HJ-cells with simple structure without high efficiency features are suffering from low Voc and Jsc. The improvement of front nip and back interface properties by adopting high quality silicon-films at low temperature should be done both for increasing device performances and production cost.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.58.2-58.2
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• 2010

본 연구에서는 n-type wafer에 비정질 실리콘을 증착한 이종접합 태양전지를 열처리 방법을 이용하여 열처리의 효과를 분석함으로써 이종접합 태양전지에 효율적인 열처리 효과에 대하여 연구하였다. P, N-layer는 PECVD(Plasma-enhanced chemical vapor deposition) I-layer는 HWCVD(Hot wire chemical vapor deposition), ITO는 RF 마그네트론 스퍼터링법으로 동일한 조건에서 제작하였고 rapid thermal process를 이용하여 진공 중에서 $150^{\circ}C$, $200^{\circ}C$, $220^{\circ}C$, $250^{\circ}C$까지 열처리를 하였다. 열처리 전과 후 QSSPC로 minority carrier life time, 자외 가시선 분광분석 장치로 투과 반사도를, Ellipsometer로 흡수 계수 등의 변화를 조사하였다. 열처리 후 Minority carrier life time, Voc 및 광변환 효율이 증가하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.129.2-129.2
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• 2011

본 연구에서는 a-Si:H/c-si 구조의 이종접합 태양전지의 p a-Si:H 에미터 층의 박막 조건에 따라 태양전지 특성을 연구하였다. p, n-layer는 PECVD (Plasma-enhanced chemical vapor deposition) i-layer는 HWCVD(Hot wire chemical vapor deposition), ITO는 RF 마그네트론 스퍼터링법으로 제작하였다. p-layer의 도핑 농도, 기판 증착 온도, 증착 높낮이에 따라 특성을 비교 분석 하였다. QSSPC로 minority carrier life time, 자외 가시선 분광분석 장치로 투과 반사도를, Ellipsometer로 흡수 계수, 두께, FTIR로 막의 구성요소 등의 변화를 조사하여 개선된 p a-Si:H의 특성이 이종접합 태양전지에서 효율향상에 영향을 주는지 Photo IV와 EQE를 통하여 조사하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.421.2-421.2
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• 2014

We report on the growth of ZnO nanorods (NRs) grown on graphite and silicon substrates via an all-solution process and characteristics of their heterojunctions. Structural investigations indicated that morphological and crystalline properties were not significantly different for the ZnO NRs on both substrates. However, optical properties from photoluminescence spectra showed that the ZnO NRs on graphite substrate contained more point defects than that on Si substrate. The ZnO NRs on both substrates showed typical rectification properties exhibiting successful diode formation. The heterojunction between the ZnO NRs and the graphite substrate showed a Schottky diode characteristic and photoresponse under ultraviolet illumination at a small reverse bias of -0.1 V. The results showed that the graphite substrate could be a good candidate for a Schottky contact electrode as well as a conducting substrate for electronic and optoelectronic applications of ZnO NRs.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.604-604
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• 2012

기존의 실리콘 이종접합 태양전지는 후면에도 passivation layer인 i-a-Si:H 및 BSF층인 n-a-Si:H가 형성되는 구조를 가지고 있었다. 이러한 구조를 대체하기 위하여 본 연구에서는 실리콘 이종접합 태양전지의 후면 구조에 passivation 층 및 BSF층을 novel material인 Sb증착 및 RTP, laser anneal을 통해 새로운 BSF층 형성하고 태양전지 특성에 대해서 분석하였다. 이를 위해서 carrier lifetime, LIV, DIV 및 QE 등 전기적, 광학적 분석뿐만 아니라 SIMS 분석을 통하여 laser annealing 공정으로 형성된 BSF층의 depth profile 분석도 진행하였다. 또한 wafer orientation에 따른 특성을 분석하기 위하여 (100) 및 (111) wafer를 이용하여 분석하였다.

• Nano
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• v.13 no.10
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• pp.1850122.1-1850122.6
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• 2018

Vertically aligned $WO_3$-CuO core-shell nanorod arrays for $NH_3$ sensing are prepared. The sensor is fabricated by preparing $WO_3$-CuO nanorod arrays directly on silicon wafer with interdigital Pt electrodes. The $WO_3$-CuO nanorod arrays are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The sensor based on the vertically aligned $WO_3$-CuO nanorod arrays exhibits ultrasensitive $NH_3$ detection, indicating p-type behavior. The optimum sensing temperature is found to be about $150^{\circ}C$. Both response and recovery time to $NH_3$ ranging from 50 ppm to 500 ppm are around 10-15 s. A possible $NH_3$ sensing mechanism of the vertically aligned hybrid nanorod arrays is proposed.