• Title/Summary/Keyword: hetero-junction

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Effect of Self-Assembled Monolayer Treated ZnO on the Photovoltaic Properties of Inverted Polymer Solar Cells

  • Yoo, Seong Il;Do, Thu Trang;Ha, Ye Eun;Jo, Mi Young;Park, Juyun;Kang, Yong-Cheol;Kim, Joo Hyun
    • Bulletin of the Korean Chemical Society
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    • v.35 no.2
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    • pp.569-574
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    • 2014
  • Inverted bulk hetero-junction polymer solar cells (iPSC) composed of P3HT/PC61BM blends on the ZnO modified with benzoic acid derivatives-based self-assembled monolayers (SAM) are fabricated. Compared with the device using the pristine ZnO, the devices with ZnO surface modified SAMs derived from benzoic acid such as 4-(diphenylamino)benzoic acid (DPA-BA) and 4-(9H-carbazol-9-yl)benzoic acid (Cz-BA) as an electron transporting layer show improved the performances. It is mainly attributed to the favorable interface dipole at the interface between ZnO and the active layer, the eective passivation of the ZnO surface traps, decrease of the work function and facilitating transport of electron from PCBM to ITO electrode. The power conversion eciency (PCE) of iPSCs based on DPA-BA and Cz-BA treated ZnO reaches 2.78 and 2.88%, respectively, while the PCE of the device based on untreated ZnO is 2.49%. The open circuit voltage values ($V_{oc}$) of the devices with bare ZnO and SAM treated ZnO are not much different. Whereas, higher the fill factor (FF) and lower the series resistance ($R_s$) are obtained in the devices with SAMs modification.

Design of Ku-Band BiCMOS Low Noise Amplifier (Ku-대역 BiCMOS 저잡음 증폭기 설계)

  • Chang, Dong-Pil;Yom, In-Bok
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.22 no.2
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    • pp.199-207
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    • 2011
  • A Ku-band low noise amplifier has been designed and fabricated by using 0.25 um SiGe BiCMOS process. The developed Ku-band LNA RFIC which has been designed with hetero-junction bipolar transistor(HBT) in the BiCMOS process have noise figure about 2.0 dB and linear gain over 19 dB in the frequency range from 9 GHz to 14 GHz. Optimization technique for p-tap value and electro-magnetic(EM) simulation technique had been used to overcome the inaccuracy in the PDK provided from the foundry service company and to supply the insufficient inductor library. The finally fabricated low noise amplifier of two fabrication runs has been implemented with the size of $0.65\;mm{\times}0.55\;mm$. The pure amplifier circuit layout with the reduced size of $0.4\;mm{\times}0.4\;mm$ without the input and output RF pads and DC bais pads has been incorporated as low noise amplication stages in the multi-function RFIC for the active phased array antenna of Ku-band satellite VSAT.

Electrical and Optical Properties of CdS Thin Films Deposited by CSVT Method (CSVT법으로 제조된 CdS박막의 전기적 및 광학적 특성)

  • Park, Ki-Cheol;Shim, Ho-Seob
    • Journal of Sensor Science and Technology
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    • v.6 no.5
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    • pp.414-422
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    • 1997
  • CdS thin films with low resistivity and adequate transmittance in the visible region for the window of CdS/CdTe hetero junction solar cel1 were prepared by close spaced vapor transport(CSVT) method. The electrical and optical properties of the CdS thin films were investigated in terms of the deposition conditions, such as the substrate temperature, the working pressure, and the source temperature. The substrate temperature, the working pressure, and the source temperature for the optimum deposition of the CdS thin films were $300^{\circ}C$, 100mTorr, and $730^{\circ}C$, respectively. The resistivity and the transmittance of the CdS thin films deposited under this condition were about $7.21{\times}10^{3}{\Omega}cm$ and over 65%, respectively. The crystallinity, the resistivity, and optical band gap were improved greatly compared to the CdS thin films deposited by general high vacuum evaporation.

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Influence of Oxygen Annealing on Temperature Dependent Electrical Characteristics of Ga2O3/4H-SiC Heterojunction Diodes (산소 후열처리가 Ga2O3/4H-SiC 이종접합 다이오드의 온도에 따른 전기적 특성에 미치는 영향 분석)

  • Chung, Seung Hwan;Lee, Hyung Jin;Lee, Hee Jae;Byun, Dong Wook;Koo, Sang Mo
    • Journal of the Semiconductor & Display Technology
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    • v.21 no.4
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    • pp.138-143
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    • 2022
  • We analyzed the influence of post-annealing on Ga2O3/n-type 4H-SiC heterojunction diode. Gallium oxide (Ga2O3) thin films were deposited by radio frequency (RF) sputtering. Post-deposition annealing at 950℃ in an Oxygen atmosphere was performed. The material properties of Ga2O3 and the electrical properties of the diodes were investigated. Atomic Force Microscopy (AFM), X-Ray Diffraction and Scanning Electron Microscope (SEM) images show a significant increase in the roughness and crystallinity of the O2-annealed films. After Oxygen annealing X-ray Photoelectron Spectroscopy (XPS) shows that the atomic ratio of oxygen increases which is related to a decrease in oxygen vacancy within the Ga2O3 film. The O2-annealed diodes exhibited higher on-current and lower leakage current. Moreover, the ideality factor, barrier height, and thermal activation energy were derived from the current-voltage curve by increasing the temperature from 298 - 434K.

Development of Radiation Image Sensor using Heterojunction (이종접합을 이용한 방사선 영상 센서 개발)

  • Kim, Young-Bin;Yun, Min-Seok;Kim, Min-Woo;Jung, Suk-Hee;Kim, Yoon-Suk;Oh, Kyung-Min;Nam, Sang-Hee;Park, Ji-Koon
    • Journal of the Korean Society of Radiology
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    • v.3 no.3
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    • pp.27-35
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    • 2009
  • In this study, the basic research verifying possibility of applications as radiology image sensor in Digital Radiography was performed, the radiology image sensor was fabricated using double layer technique tio decrease dark current. High efficiency material in substitution for a-Se have been studied as a direct method of imaging detector in Digital Radiography to decrease dark current by using Hetero junction already used as solar cell, semiconductor. Particle-In-Binder method is used to fabricate radiology image sensor because it has a lot of advantages such as fabrication convenient, high yield, suitability for large area sensor. But high leakage current is one of main problem in PIB method. To make up for the weak points, double layer technique is used, and it is considered that high efficient digital radiation sensor can be fabricated with easy and convenient process. In this study, electrical properties such as leakage current, sensitivity is measured to evaluate double layer radiation sensor material.

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Effect of Cleaning Processes of Silicon Wafer on Surface Passivation and a-Si:H/c-Si Hetero-Junction Solar Cell Performances (기판 세정특성에 따른 표면 패시배이션 및 a-Si:H/c-Si 이종접합 태양전지 특성변화 분석)

  • Song, Jun-Yong;Jeong, Dae-Young;Kim, Chan-Seok;Park, Sang-Hyun;Cho, Jun-Sik;Song, Jin-Soo;Wang, Jin-Suk;Lee, Jeong-Chul
    • 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.

Effects of Organic Passivation Films on Properties of Polymer Solar Cells with P3HT:PC61BM Active Layers (유기 패시베이션 박막이 P3HT:PC61BM 활성층을 갖는 고분자 태양전지의 특성에 미치는 영향)

  • Lee, Sang Hee;Park, Byung Min;Cho, Yang Keun;Chang, Ho Jung;Jung, Jae Jin;Pyee, Jaeho
    • Journal of the Microelectronics and Packaging Society
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    • v.21 no.4
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    • pp.105-110
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    • 2014
  • It is required to improve the efficiency and the reliability of the polymer solar cells (PSCs) as the energy saving optical device for the future application of the smart farm facilities. In this study, we fabricated the bulk hetero junction PSCs with organic passivation film layer for the reliability improvement of the devices. The effects of the passivation layer on the electrical properties of the PSCs were studied. The materials of passivation layer are composed of poly vinyl alcohol (PVA) and ammonium dichromate, and the passivation films were fabricated by the spin coating method on the P3HT:$PC_{61}BM$/LiF/Al substrate. The prepared structure of the device is the glass/ITO/PEDOT:PSS/P3HT:$PC_{61}BM$/LiF/Al/passivation layer. The performances of the PSCs with the organic passivation film showed better electrical properties compared with the PSCs without passivation layers. The power conversion efficiency (PCE) values of passivated PSCs decreased from 3.0 to 1.3% after air exposure for 140 hrs. In contrast, the PCE values for the devices without passivation decreased sharply from 3.5 to 0.1% under the same exposure condition.

Study on Improvement of Signal to Noise Ratio for HgI2 Radiation Conversion Sensor Using Blocking Layer (Blocking layer 적용을 통한 HgI2 방사선 변환센서의 신호대 잡음비 향상에 관한 연구)

  • Park, Ji-Koon;Yoon, In-Chan;Choi, Su-Rim;Yoon, Ju-Sun;Lee, Young-Kyu;Kang, Sang-Sik
    • Journal of the Korean Society of Radiology
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    • v.5 no.2
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    • pp.97-101
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    • 2011
  • In this study, the basic research verifying possibility of applications as radiology image sensor in Digital Radiography was performed, the radiology image sensor was fabricated using double layer technique tio decrease dark current. High efficiency material in substitution for a-Se have been studied as a direct method of imaging detector in Digital Radiography to decrease dark current by using Hetero junction already used as solar cell, semiconductor. Particle-In-Binder method is used to fabricate radiology image sensor because it has a lot of advantages such as fabrication convenient, high yield, suitability for large area sensor. But high leakage current is one of main problem in PIB method. To make up for the weak points, double layer technique is used, and it is considered that high efficient digital radiation sensor can be fabricated with easy and convenient process. In this study, electrical properties such as leakage current, sensitivity is measured to evaluate double layer radiation sensor material.