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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal DOI :
Electronics and Telecommunications Research Institute
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Volume & Issues
Volume 35, Issue 6 - Dec 2013
Volume 35, Issue 5 - Oct 2013
Volume 35, Issue 4 - Aug 2013
Volume 35, Issue 3 - Jun 2013
Volume 35, Issue 2 - Apr 2013
Volume 35, Issue 1 - Feb 2013
Selecting the target year
Transparent OLED Lighting Panel Design Using Two-Dimensional OLED Circuit Modeling
Han, Jun-Han ; Moon, Jaehyun ; Cho, Doo-Hee ; Shin, Jin-Wook ; Joo, Chul Woong ; Hwang, Joohyun ; Huh, Jin Woo ; Chu, Hye Yong ; Lee, Jeong-Ik ;
ETRI Journal, volume 35, issue 4, 2013, Pages 559~565
DOI : 10.4218/etrij.13.1912.0020
In this work, we develop a simulation method to predict a two-dimensional luminance distribution method using a circuitry simulation. Based on the simulation results, we successfully fabricate large area (
) transparent organic light-emitting diode panels with high luminance uniformity.
380-nm Ultraviolet Light-Emitting Diodes with InGaN/AlGaN MQW Structure
Bae, Sung-Bum ; Kim, Sung-Bok ; Kim, Dong-Churl ; Nam, Eun Soo ; Lim, Sung-Mook ; Son, Jeong-Hwan ; Jo, Yi-Sang ;
ETRI Journal, volume 35, issue 4, 2013, Pages 566~570
DOI : 10.4218/etrij.13.1912.0029
In this paper, we demonstrate the capabilities of 380-nm ultraviolet (UV) light-emitting diodes (LEDs) using metal organic chemical vapor deposition. The epi-structure of these LEDs consists of InGaN/AlGaN multiple quantum wells on a patterned sapphire substrate, and the devices are fabricated using a conventional LED process. The LEDs are packaged with a type of surface mount device with Al-metal. A UV LED can emit light at 383.3 nm, and its maximum output power is 118.4 mW at 350 mA.
Preliminary Works of Contact via Formation of LCD Backplanes Using Silver Printing
Yang, Yong Suk ; You, In-Kyu ; Han, Hyun ; Koo, Jae Bon ; Lim, Sang Chul ; Jung, Soon-Won ; Na, Bock Soon ; Kim, Hye-Min ; Kim, Minseok ; Moon, Seok-Hwan ;
ETRI Journal, volume 35, issue 4, 2013, Pages 571~577
DOI : 10.4218/etrij.13.1912.0018
The fabrication of a thin-film transistor backplane and a liquid-crystal display using printing processes can eliminate the need for photolithography and offers the potential to reduce the manufacturing costs. In this study, we prepare contact via structures through a poly(methyl methacrylate) polymer insulator layer using inkjet printing. When droplets of silver ink composed of a polymer solvent are placed onto the polymer insulator and annealed at high temperatures, the silver ink penetrates the interior of the polymer and generates conducting paths between the top and bottom metal lines through the partial dissolution and swelling of the polymer. The electrical property of various contact via-hole interconnections is investigated using a semiconductor characterization system.
Design and Experiment Results of High-Speed Wireless Link Using Sub-terahertz Wave Generated by Photonics-Based Technology
Kim, Sungil ; Ahn, Seung-Ho ; Park, Seong Su ;
ETRI Journal, volume 35, issue 4, 2013, Pages 578~586
DOI : 10.4218/etrij.13.1912.0017
Using a sub-terahertz (sub-THz) wave generated using a photonics-based technology, a high-speed wireless link operating at up to 10 Gbps is designed and demonstrated for realization of seamless connectivity between wireless and wired networks. The sub-THz region is focused upon because of the possibility to obtain sufficient bandwidth without interference with the allocated RF bands. To verify the high-speed wireless link, such dynamic characteristics as the eye diagrams and bit error rate (BER) are measured at up to 10 Gbps for non-return-to-zero pseudorandom binary sequence
data. From the measurement results, a receiver sensitivity of -23.5 dBm at
is observed without any error corrections when the link distance between the transmitter and receiver is 3 m. Consequently, we hope that our design and experiment results will be helpful in implementing a high-speed wireless link using a sub-THz wave.
Thin Metal Electrodes for Semitransparent Organic Photovoltaics
Lee, Kyu-Sung ; Kim, Inho ; Yeon, Chang Bong ; Lim, Jung Wook ; Yun, Sun Jin ; Jabbour, Ghassan E. ;
ETRI Journal, volume 35, issue 4, 2013, Pages 587~593
DOI : 10.4218/etrij.13.1912.0025
We demonstrate semitransparent organic photovoltaics (OPVs) based on thin metal electrodes and polymer photoactive layers consisting of poly(3-hexylthiophene) and [6,6]-phenyl
butyric acid methyl ester. The power conversion efficiency of a semitransparent OPV device comprising a 15-nm silver (Ag) rear electrode is 1.98% under AM 1.5-G illumination through the indium-tin-oxide side of the front anode at 100
with 15.6% average transmittance of the entire cell in the visible wavelength range. As its thickness increases, a thin Ag electrode mainly influences the enhancement of the short circuit current density and fill factor. Its relatively low absorption intensity makes a Ag thin film a viable option for semitransparent electrodes compatible with organic layers.
Printed Organic One-Time Programmable ROM Array Using Anti-fuse Capacitor
Yang, Byung-Do ; Oh, Jae-Mun ; Kang, Hyeong-Ju ; Jung, Soon-Won ; Yang, Yong Suk ; You, In-Kyu ;
ETRI Journal, volume 35, issue 4, 2013, Pages 594~602
DOI : 10.4218/etrij.13.1912.0010
This paper proposes printed organic one-time programmable read-only memory (PROM). The organic PROM cell consists of a capacitor and an organic p-type metal-oxide semiconductor (PMOS) transistor. Initially, all organic PROM cells with unbroken capacitors store "0." Some organic PROM cells are programmed to "1" by electrically breaking each capacitor with a high voltage. After the capacitor breaking, the current flowing through the PROM cell significantly increases. The memory data is read out by sensing the current in the PROM cell. 16-bit organic PROM cell arrays are fabricated with the printed organic PMOS transistor and capacitor process. The organic PROM cells are programmed with -50 V, and they are read out with -20 V. The area of the 16-bit organic PROM array is 70.6
Reverse-Conducting IGBT Using MEMS Technology on the Wafer Back Side
Won, Jongil ; Koo, Jin Gun ; Rhee, Taepok ; Oh, Hyung-Seog ; Lee, Jin Ho ;
ETRI Journal, volume 35, issue 4, 2013, Pages 603~609
DOI : 10.4218/etrij.13.1912.0030
In this paper, we present a 600-V reverse conducting insulated gate bipolar transistor (RC-IGBT) for soft and hard switching applications, such as general purpose inverters. The newly developed RC-IGBT uses the deep reactive-ion etching trench technology without the thin wafer process technology. Therefore, a freewheeling diode (FWD) is monolithically integrated in an IGBT chip. The proposed RC-IGBT operates as an IGBT in forward conducting mode and as an FWD in reverse conducting mode. Also, to avoid the destructive failure of the gate oxide under the surge current and abnormal conditions, a protective Zener diode is successfully integrated in the gate electrode without compromising the operation performance of the IGBT.
A Transparent Logic Circuit for RFID Tag in a-IGZO TFT Technology
Yang, Byung-Do ; Oh, Jae-Mun ; Kang, Hyeong-Ju ; Park, Sang-Hee ; Hwang, Chi-Sun ; Ryu, Min Ki ; Pi, Jae-Eun ;
ETRI Journal, volume 35, issue 4, 2013, Pages 610~616
DOI : 10.4218/etrij.13.1912.0004
This paper proposes a transparent logic circuit for radio frequency identification (RFID) tags in amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) technology. The RFID logic circuit generates 16-bit code programmed in read-only memory. All circuits are implemented in a pseudo-CMOS logic style using transparent a-IGZO TFTs. The transmittance degradation due to the transparent RFID logic chip is 2.5% to 8% in a 300-nm to 800-nm wavelength. The RFID logic chip generates Manchester-encoded 16-bit data with a 3.2-kHz clock frequency and consumes 170
V. It employs 222 transistors and occupies a chip area of 5.85
Semiconductor-Type MEMS Gas Sensor for Real-Time Environmental Monitoring Applications
Moon, Seung Eon ; Choi, Nak-Jin ; Lee, Hyung-Kun ; Lee, Jaewoo ; Yang, Woo Seok ;
ETRI Journal, volume 35, issue 4, 2013, Pages 617~624
DOI : 10.4218/etrij.13.1912.0008
Low power consuming and highly responsive semiconductor-type microelectromechanical systems (MEMS) gas sensors are fabricated for real-time environmental monitoring applications. This subsystem is developed using a gas sensor module, a Bluetooth module, and a personal digital assistant (PDA) phone. The gas sensor module consists of a
or CO gas sensor and signal processing chips. The MEMS gas sensor is composed of a microheater, a sensing electrode, and sensing material. Metal oxide nanopowder is drop-coated onto a substrate using a microheater and integrated into the gas sensor module. The change in resistance of the metal oxide nanopowder from exposure to oxidizing or deoxidizing gases is utilized as the principle mechanism of this gas sensor operation. The variation detected in the gas sensor module is transferred to the PDA phone by way of the Bluetooth module.
Optimization of Material and Process for Fine Pitch LVSoP Technology
Eom, Yong-Sung ; Son, Ji-Hye ; Bae, Hyun-Cheol ; Choi, Kwang-Seong ; Choi, Heung-Soap ;
ETRI Journal, volume 35, issue 4, 2013, Pages 625~631
DOI : 10.4218/etrij.13.1912.0007
For the formation of solder bumps with a fine pitch of 130
on a printed circuit board substrate, low-volume solder on pad (LVSoP) technology using a maskless method is developed for SAC305 solder with a high melting temperature of
. The solder bump maker (SBM) paste and its process are quantitatively optimized to obtain a uniform solder bump height, which is almost equal to the height of the solder resist. For an understanding of chemorheological phenomena of SBM paste, differential scanning calorimetry, viscosity measurement, and physical flowing of SBM paste are precisely characterized and observed during LVSoP processing. The average height of the solder bumps and their maximum and minimum values are 14.7
, and 12.0
, respectively. It is expected that maskless LVSoP technology can be effectively used for a fine-pitch interconnection of a Cu pillar in the semiconductor packaging field.
Fabrication of Superjunction Trench Gate Power MOSFETs Using BSG-Doped Deep Trench of p-Pillar
Kim, Sang Gi ; Park, Hoon Soo ; Na, Kyoung Il ; Yoo, Seong Wook ; Won, Jongil ; Koo, Jin Gun ; Chai, Sang Hoon ; Park, Hyung-Moo ; Yang, Yil Suk ; Lee, Jin Ho ;
ETRI Journal, volume 35, issue 4, 2013, Pages 632~637
DOI : 10.4218/etrij.13.1912.0012
In this paper, we propose a superjunction trench gate MOSFET (SJ TGMOSFET) fabricated through a simple p-pillar forming process using deep trench and boron silicate glass doping process technology to reduce the process complexity. Throughout the various boron doping experiments, as well as the process simulations, we optimize the process conditions related with the p-pillar depth, lateral boron doping concentration, and diffusion temperature. Compared with a conventional TGMOSFET, the potential of the SJ TGMOSFET is more uniformly distributed and widely spread in the bulk region of the n-drift layer due to the trenched p-pillar. The measured breakdown voltage of the SJ TGMOSFET is at least 28% more than that of a conventional device.
A Broadband Digital Step Attenuator with Low Phase Error and Low Insertion Loss in 0.18-
SOI CMOS Technology
Cho, Moon-Kyu ; Kim, Jeong-Geun ; Baek, Donghyun ;
ETRI Journal, volume 35, issue 4, 2013, Pages 638~643
DOI : 10.4218/etrij.13.0112.0534
This paper presents a 5-bit digital step attenuator (DSA) using a commercial 0.18-
silicon-on-insulator (SOI) process for the wideband phased array antenna. Both low insertion loss and low root mean square (RMS) phase error and amplitude error are achieved employing two attenuation topologies of the switched path attenuator and the switched T-type attenuator. The attenuation coverage of 31 dB with a least significant bit of 1 dB is achieved at DC to 20 GHz. The RMS phase error and amplitude error are less than
and less than 0.5 dB, respectively. The measured insertion loss of the reference state is less than 5.5 dB at 10 GHz. The input return loss and output return loss are each less than 12 dB at DC to 20 GHz. The current consumption is nearly zero with a voltage supply of 1.8 V. The chip size is
, including pads. To the best of the authors' knowledge, this is the first demonstration of a low phase error DC-to-20-GHz SOI DSA.
Frequency Domain DTV Pilot Detection Based on the Bussgang Theorem for Cognitive Radio
Hwang, Sung Sue ; Park, Dong Chan ; Kim, Suk Chan ;
ETRI Journal, volume 35, issue 4, 2013, Pages 644~654
DOI : 10.4218/etrij.13.0112.0556
In this paper, a signal detection scheme for cognitive radio (CR) based on the Bussgang theorem is proposed. The proposed scheme calculates the statistical difference between Gaussian noise and the primary user signal by applying the Bussgang theorem to the received signal. Therefore, the proposed scheme overcomes the noise uncertainty and gives scalable complexity according to the zero-memory nonlinear function for a mobile device. We also present the theoretical analysis on the detection threshold and the detection performance in the additive white Gaussian noise channel. The proposed detection scheme is evaluated by computer simulations based on the IEEE 802.22 standard for the wireless regional area network. Our results show that the proposed scheme is robust to the noise uncertainty and works well in a very low signal-to-noise ratio.
An Efficient Transmission Scheme of MPEG2-TS over RTP for a Hybrid DMB System
Seo, Hyung-Yoon ; Bae, Byungjun ; Kim, Jong-Deok ;
ETRI Journal, volume 35, issue 4, 2013, Pages 655~665
DOI : 10.4218/etrij.13.0112.0124
Hybrid digital multimedia broadcasting (DMB) is a next-generation mobile TV system that combines broadcasting and wireless communication networks and can provide various high-quality multimedia services. However, if a system adheres to the current standard of transmitting the DMB content in the form of MPEG2-TS through wireless networks, it results in a burden on the network due to low transmission efficiency. The reasons for the low transmission efficiency are as follows. First, due to its constant bitrate characteristic, DMB MPEG2-TS includes a considerable amount of needless information, such as NULL packets and stuffing bytes. Second, due to the inflexibility of the Real-time Transport Protocol (RTP) standard, one cannot fully utilize the maximum transmission unit of the network when converting MPEG2-TS to RTP stream for transmission. This paper proposes a new transmission scheme that resolves these problems. Experiment results show that the proposed scheme improves data bitrate transmission efficiency by 8% to 36%, compared to the standard scheme, in the streaming of various real-DMB contents.
Mobile Oriented Future Internet (MOFI): Architectural Design and Implementations
Kim, Ji-In ; Jung, Heeyoung ; Koh, Seok-Joo ;
ETRI Journal, volume 35, issue 4, 2013, Pages 666~676
DOI : 10.4218/etrij.13.1812.0064
With the recent growth in smartphone services, the "mobile" environment has become a key factor to consider in the design of the future Internet. In this paper, we propose Mobile-Oriented Future Internet (MOFI), which is a new architecture for the future Internet for mobile-oriented environments. The MOFI architecture is designed with three functional features: global identifier and local locator in the identifier-locator separation, query-first data delivery for route optimization, and distributed control of identifier-locator mapping. The proposed architecture and functional operations are implemented and tested using the Linux platform. From the experiment results, we see that the MOFI architecture performs better than the existing identifier-locator separation schemes, such as Proxy Mobile IP and Host Identity Protocol, in terms of data throughout, mapping control overhead, and handover delay.
An Optimal Power Scheduling Method Applied in Home Energy Management System Based on Demand Response
Zhao, Zhuang ; Lee, Won Cheol ; Shin, Yoan ; Song, Kyung-Bin ;
ETRI Journal, volume 35, issue 4, 2013, Pages 677~686
DOI : 10.4218/etrij.13.0112.0625
In this paper, we first introduce a general architecture of an energy management system in a home area network based on a smart grid. Then, we propose an efficient scheduling method for home power usage. The home gateway (HG) receives the demand response (DR) information indicating the real-time electricity price, which is transferred to an energy management controller (EMC). Referring to the DR, the EMC achieves an optimal power scheduling scheme, which is delivered to each electric appliance by the HG. Accordingly, all appliances in the home operate automatically in the most cost-effective way possible. In our research, to avoid the high peak-to-average ratio (PAR) of power, we combine the real-time pricing model with the inclining block rate model. By adopting this combined pricing model, our proposed power scheduling method effectively reduces both the electricity cost and the PAR, ultimately strengthening the stability of the entire electricity system.
Cache Optimization on Hot-Point Proxy Caching Using Weighted-Rank Cache Replacement Policy
Ponnusamy, S.P. ; Karthikeyan, E. ;
ETRI Journal, volume 35, issue 4, 2013, Pages 687~696
DOI : 10.4218/etrij.13.0112.0606
The development of proxy caching is essential in the area of video-on-demand (VoD) to meet users' expectations. VoD requires high bandwidth and creates high traffic due to the nature of media. Many researchers have developed proxy caching models to reduce bandwidth consumption and traffic. Proxy caching keeps part of a media object to meet the viewing expectations of users without delay and provides interactive playback. If the caching is done continuously, the entire cache space will be exhausted at one stage. Hence, the proxy server must apply cache replacement policies to replace existing objects and allocate the cache space for the incoming objects. Researchers have developed many cache replacement policies by considering several parameters, such as recency, access frequency, cost of retrieval, and size of the object. In this paper, the Weighted-Rank Cache replacement Policy (WRCP) is proposed. This policy uses such parameters as access frequency, aging, and mean access gap ratio and such functions as size and cost of retrieval. The WRCP applies our previously developed proxy caching model, Hot-Point Proxy, at four levels of replacement, depending on the cache requirement. Simulation results show that the WRCP outperforms our earlier model, the Dual Cache Replacement Policy.
Folded Architecture for Digital Gammatone Filter Used in Speech Processor of Cochlear Implant
Karuppuswamy, Rajalakshmi ; Arumugam, Kandaswamy ; Swathi, Priya M. ;
ETRI Journal, volume 35, issue 4, 2013, Pages 697~705
DOI : 10.4218/etrij.13.0112.0220
Emerging trends in the area of digital very large scale integration (VLSI) signal processing can lead to a reduction in the cost of the cochlear implant. Digital signal processing algorithms are repetitively used in speech processors for filtering and encoding operations. The critical paths in these algorithms limit the performance of the speech processors. These algorithms must be transformed to accommodate processors designed to be high speed and have less area and low power. This can be realized by basing the design of the auditory filter banks for the processors on digital VLSI signal processing concepts. By applying a folding algorithm to the second-order digital gammatone filter (GTF), the number of multipliers is reduced from five to one and the number of adders is reduced from three to one, without changing the characteristics of the filter. Folded second-order filter sections are cascaded with three similar structures to realize the eighth-order digital GTF whose response is a close match to the human cochlea response. The silicon area is reduced from twenty to four multipliers and from twelve to four adders by using the folding architecture.
Robust CFO Acquisition in PN-Padded OFDM Systems
Liu, Guanghui ; Zeng, Liaoyuan ; Li, Hongliang ; Xu, Linfeng ; Wang, Zhengning ;
ETRI Journal, volume 35, issue 4, 2013, Pages 706~709
DOI : 10.4218/etrij.13.0212.0431
As an alternative to the traditional pilot-aided orthogonal frequency division multiplexing (OFDM), the time-domain pseudonoise (PN)-padded OFDM provides a higher spectral efficiency. However, the carrier frequency offset (CFO) attenuates peaks of the conventional PN correlation output, which limits the CFO estimation range of the OFDM synchronizer. An improved correlation is proposed in this letter to remove the CFO-induced amplitude attenuation of correlation peaks. For a synchronizer adopting the designed correlator, a larger range of CFO acquisition is obtained through using wider correlation windows with a smaller interval between them. The proposed method of CFO acquisition is verified in a digital terrestrial multimedia broadcast receiver, in which the synchronizer is able to acquire CFOs up to
kHz in the DVB-T F1 channel. Furthermore, the acquisition range can be expanded in more favorable channels.
OFDM-Based STBC with Low End-to-End Delay for Full-Duplex Asynchronous Cooperative Systems
Jiang, Hua ; Xing, Xianglei ; Zhao, Kanglian ; Du, Sidan ;
ETRI Journal, volume 35, issue 4, 2013, Pages 710~713
DOI : 10.4218/etrij.13.0212.0495
We propose a new space-time block coding (STBC) for asynchronous cooperative systems in full-duplex mode. The orthogonal frequency division multiplexing (OFDM) transmission technique is used to combat the timing errors from the relay nodes. At the relay nodes, only one OFDM time slot is required to delay for a pair-wise symbol swap operation. The decoding complexity is lower for this new STBC than for the traditional quasi-orthogonal STBC. Simulation results show that the proposed scheme achieves excellent performances.
Reducing the PAPR of OFDM Systems by Random Variable Transformation
Taher, Montadar Abas ; Singh, Mandeep Jit ; Ismail, Mahamod Bin ; Samad, Salina Abdul ; Islam, Mohammad Tariqul ;
ETRI Journal, volume 35, issue 4, 2013, Pages 714~717
DOI : 10.4218/etrij.13.0212.0552
Peak power reduction techniques in orthogonal frequency division multiplexing (OFDM) has been an important subject for many researchers for over 20 years. In this letter, we propose a side-information-free technique that is based on the concept of random variable (RV) transformation. The suggested method transforms RVs into other RVs, aiming to reshape the constellation that will consequently produce OFDM symbols with a reduced peak-to-average power ratio. The proposed method has no limitation on the mapping type or the mapping order and has no significant effect on the bit error rate performance compared to other methods presented in the literature. Additionally, the computational complexity does not increase.
Adaptive Calibration Method in Multiport Amplifier for K-Band Payload Applications
Moon, Seong-Mo ; Shin, Dong-Hwan ; Lee, Hong-Yul ; Uhm, Man-Seok ; Yom, In-Bok ; Lee, Moon-Que ;
ETRI Journal, volume 35, issue 4, 2013, Pages 718~721
DOI : 10.4218/etrij.13.0212.0534
This letter proposes a novel calibration method for a multiport amplifier (MPA) to achieve optimum port-to-port isolation by correcting both the amplitude and phase of the calibration signals. The proposed architecture allows for the detection of the phase error and amplitude error in each RF signal path simultaneously and can enhance the calibrated resolution by controlling the analog phase shifters and attenuators. The designed
MPAs show isolation characteristics of 30 dB and 27 dB over a frequency range of 19.5 GHz to 22.5 GHz, respectively.
Second-Order Statistics of System with Microdiversity and Macrodiversity Reception in Gamma-Shadowed Rician Fading Channels
Bandjur, Milos ; Sekulovic, Nikola ; Stefanovic, Mihajlo ; Golubovic, Aleksandra ; Spalevic, Petar ; Milic, Dejan ;
ETRI Journal, volume 35, issue 4, 2013, Pages 722~725
DOI : 10.4218/etrij.13.0212.0370
In this letter, a wireless communication system with microdiversity and macrodiversity reception in gamma-shadowed Rician fading channels is considered. Exact and rapidly converging infinite-series expressions for the average level crossing rate and average fade duration at the output of the system are provided. Numerical results are presented graphically to illustrate the proposed mathematical analysis and to examine the effects of the system's parameters on the quantities considered.
Securing RTP Packets Using Per-Packet Key Exchange for Real-Time Multimedia
Jung, Younchan ; Festijo, Enrique ; Atwood, J. William ;
ETRI Journal, volume 35, issue 4, 2013, Pages 726~729
DOI : 10.4218/etrij.13.0212.0549
For secure multimedia communications, existing encryption techniques use an online session key for the key exchange, for which key size is limited to less than 10 digits to accommodate the latency condition caused by user devices only being able to handle low computational loads. This condition results in poor security of recorded encrypted data. In this letter, we propose a packet key scheme that encrypts real-time packets using a different key per packet for multimedia applications. Therefore, a key of a relatively small size can provide after-transmission confidentiality to data of a real-time session.
The Characteristics of a Hydrogenated Amorphous Silicon Semitransparent Solar Cell When Applying n/i Buffer Layers
Lee, Da Jung ; Yun, Sun Jin ; Lee, Seong Hyun ; Lim, Jung Wook ;
ETRI Journal, volume 35, issue 4, 2013, Pages 730~733
DOI : 10.4218/etrij.13.0212.0402
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.
Nonvolatile Ferroelectric P(VDF-TrFE) Memory Transistors Based on Inkjet-Printed Organic Semiconductor
Jung, Soon-Won ; Na, Bock Soon ; Baeg, Kang-Jun ; Kim, Minseok ; Yoon, Sung-Min ; Kim, Juhwan ; Kim, Dong-Yu ; You, In-Kyu ;
ETRI Journal, volume 35, issue 4, 2013, Pages 734~737
DOI : 10.4218/etrij.13.0212.0280
Nonvolatile ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) memory based on an organic thin-film transistor with inkjet-printed dodecyl-substituted thienylenevinylene-thiophene copolymer (PC12TV12T) as the active layer is developed. The memory window is 4.5 V with a gate voltage sweep of -12.5 V to 12.5 V. The field effect mobility, on/off ratio, and gate leakage current are 0.1
A, respectively. Although the retention behaviors should be improved and optimized, the obtained characteristics are very promising for future flexible electronics.