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Won J.,Components and Materials Research Laboratory | Koo J.G.,Components and Materials Research Laboratory | Rhee T.,Semicon Device | Lee J.H.,Components and Materials Research Laboratory
ETRI Journal | Year: 2013

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. © 2013 ETRI.

An B.W.,Wearable Electronics Research Group | Hyun B.G.,Wearable Electronics Research Group | Kim S.-Y.,Wearable Electronics Research Group | Kim M.,Wearable Electronics Research Group | And 7 more authors.
Nano Letters | Year: 2014

Transparent electrodes that can maintain their electrical and optical properties stably against large mechanical deformations are essential in numerous applications of flexible and wearable electronics. In this paper, we report a comprehensive analysis of the electrical, optical, and mechanical properties of hybrid nanostructures based on graphene and metal nanotrough networks as stretchable and transparent electrodes. Compared to the single material of graphene or the nanotrough, the formation of this hybrid can improve the uniformity of sheet resistance significantly, that is, a very low sheet resistance (1 Ω/sq) with a standard deviation of less than ±0.1 Ω/sq, high transparency (91% in the visible light regime), and superb stretchability (80% in tensile strain). The successful demonstration of skin-attachable, flexible, and transparent arrays of oxide semiconductor transistors fabricated using hybrid electrodes suggests substantial promise for the next generation of electronic devices. © 2014 American Chemical Society.

Kwon O.K.,Components and Materials Research Laboratory | Beak Y.S.,Components and Materials Research Laboratory | Chung Y.C.,Korea Advanced Institute of Science and Technology | Park H.-M.,Dongguk University
ETRI Journal | Year: 2013

A novel integrated laser, that is, a distributed reflector laser diode integrated with an electroabsorption modulator, is proposed to improve the output efficiency, single-mode stability, and chirp. The proposed laser can be realized using the selective metalorganic vapor phase epitaxy technique (that is, control of the width of the insulating mask), and its fabrication process is almost the same as the conventional electroabsorption modulated laser (EML) process except for the asymmetric coupling coefficient structure along the cavity. For our analysis, an accurate time-domain transfer-matrix-based laser model is developed. Based on this model, we perform steady-state and large-signal analyses. The performances of the proposed laser, such as the output power, extinction ratio, and chirp, are compared with those of the EML. Under 10-Gbps NRZ modulation, we can obtain a 30% higher output power and about 50% lower chirp than the conventional EML. In particular, the simulation results show that the chirp provided by the proposed laser can appear to have a longer wavelength side at the leading edge of the pulse and a shorter wavelength side at the falling edge. © 2013 ETRI.

Seo H.S.,Components and Materials Research Laboratory | Park B.J.,Components and Materials Research Laboratory | Choi H.R.,Chungnam National University | Ahn J.T.,Components and Materials Research Laboratory
Journal of Non-Crystalline Solids | Year: 2015

We introduce a core-on-clad (COC) method for the fabrication of mid-IR fibers using a single crucible, which is different from a conventional double crucible process. The COC method involves stacking a core rod on a cladding rod in the single crucible and drawing it into the optical fiber directly. With this method, we developed a mid-IR fiber having a core-clad diameter ratio of 90%. By inserting a steel ring between the core and clad rods, the core-clad ratio was further reduced by about 82% and 52%, which depended on the inner hole sizes of the ring. After purification of raw materials, the transmission loss was measured at 1.2. dB/m for the wavelength of 3. μm and 0.26. dB/m for 5. μm. These large core mid-IR fibers can be applied for the beam delivery of medical lasers such as Er-YAG. © 2015 Elsevier B.V.

Seo M.,Sungkyunkwan University | Nam E.,Components and Materials Research Laboratory | Rodwell M.,University of California at Santa Barbara
ETRI Journal | Year: 2014

Blind mismatch correction of time-interleaved analog-to-digital converters (TI-ADC) is a challenging task. We present a practical blind calibration technique for low-computation, low-complexity, and high-resolution applications. Its key features are: dramatically reduced computation; simple hardware; guaranteed parameter convergence with an arbitrary number of TI-ADC channels and most real-life input signals, with no bandwidth limitation; multiple Nyquist zone operation; and mixed-domain error correction. The proposed technique is experimentally verified by an M = 4 400 MSPS TI-ADC system. In a single-tone test, the proposed practical blind calibration technique suppressed mismatch spurs by 70 dB to 90 dB below the signal tone across the first two Nyquist zones (10 MHz to 390 MHz). A wideband signal test also confirms the proposed technique. © 2014 ETRI.

Eom Y.-S.,Components and Materials Research Laboratory | Son J.-H.,Components and Materials Research Laboratory | Jang K.-S.,Case Western Reserve University | Lee H.-S.,Components and Materials Research Laboratory | And 3 more authors.
ETRI Journal | Year: 2014

For the fine-pitch application of flip-chip bonding with semiconductor packaging, fluxing and hybrid underfills were developed. A micro-encapsulated catalyst was adopted to control the chemical reaction at room and processing temperatures. From the experiments with a differential scanning calorimetry and viscometer, the chemical reaction and viscosity changes were quantitatively characterized, and the optimum type and amount of micro-encapsulated catalyst were determined to obtain the best pot life from a commercial viewpoint. It is expected that fluxing and hybrid underfills will be applied to fine-pitch flip-chip bonding processes and be highly reliable. © 2014 ETRI.

Bae H.-C.,Components and Materials Research Laboratory | Lee H.,Components and Materials Research Laboratory | Choi K.-S.,Components and Materials Research Laboratory | Eom Y.-S.,Components and Materials Research Laboratory
ETRI Journal | Year: 2013

A cost-effective and simple solder on pad (SoP) process is proposed for a fine-pitch microbump interconnection. A novel solder bump maker (SBM) material is applied to form a 60-μm pitch SoP. SBM, which is composed of ternary Sn3.0Ag0.5Cu (SAC305) solder powder and a polymer resin, is a paste material used to perform a fine-pitch SoP through a screen printing method. By optimizing the volumetric ratio of the resin, deoxidizing agent, and SAC305 solder powder, the oxide layers on the solder powder and Cu pads are successfully removed during the bumping process without additional treatment or equipment. Test vehicles with a daisy chain pattern are fabricated to develop the fine-pitch SoP process and evaluate the fine-pitch interconnection. The fabricated Si chip has 6,724 bumps with a 45-μm diameter and 60-μm pitch. The chip is flip chip bonded with a Si substrate using an underfill material with fluxing features. Using the fluxing underfill material is advantageous since it eliminates the flux cleaning process and capillary flow process of the underfill. The optimized bonding process is validated through an electrical characterization of the daisy chain pattern. This work is the first report on a successful operation of a fine-pitch SoP and microbump interconnection using a screen printing process. © 2013 ETRI.

Lee S.H.,Components and Materials Research Laboratory | Yun S.J.,Components and Materials Research Laboratory | Lim J.W.,Components and Materials Research Laboratory
ETRI Journal | Year: 2013

We investigate the characteristics of Cu2O thin films deposited through the addition of N2 gas. The addition of N2 gas has remarkable effects on the phase changes, resulting in improved electrical and optical properties. An intermediate phase (6CuO·Cu2O) appears at a N2 flow rate of 1 sccm, and a Cu2O (200) phase is then preferentially grown at a higher feeding amount of N2. The optical and electrical properties of Cu2O thin films are improved with a sufficient N2 flow rate of more than 15 sccm, as confirmed through various analyses. Under this condition, a high bandgap energy of 2.58 eV and a conductivity of 1.5×10-2 S/cm are obtained. These high-quality Cu2O thin films are expected to be applied to Cu2O-based heterojunction solar cells and optical functional films. © 2013 ETRI.

Lee D.J.,Components and Materials Research Laboratory | Yun S.J.,Components and Materials Research Laboratory | Lee S.H.,Components and Materials Research Laboratory | Lim J.W.,Components and Materials Research Laboratory
ETRI Journal | Year: 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. © 2013 ETRI.

Lho Y.H.,Woosong University | Yang Y.-S.,Components and Materials Research Laboratory
ETRI Journal | Year: 2015

For a conventional power metal-oxide-semiconductor field-effect transistor (MOSFET), there is a trade-off between specific on-state resistance and breakdown voltage. To overcome this trade-off, a super-junction trench MOSFET (TMOSFET) structure is suggested; within this structure, the ability to sense the temperature distribution of the TMOSFET is very important since heat is generated in the junction area, thus affecting its reliability. Generally, there are two types of temperaturesensing structures - diode and resistive. In this paper, a diode-type temperature-sensing structure for a TMOSFET is designed for a brushless direct current motor with on-resistance of 96 mΩ·mm2. The temperature distribution for an ultra-low on-resistance power MOSFET has been analyzed for various bonding schemes. The multi-bonding and stripe bonding cases show a maximum temperature that is lower than that for the single-bonding case. It is shown that the metal resistance at the source area is non-negligible and should therefore be considered depending on the application for current driving capability. © 2015 ETRI.

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