• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05a
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• pp.53-56
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• 2004

The a-Si:H TFT using ferroelectric of SrTi $O_3$as a gate insulator is fabricated on glass. Dielectric characteristics of ferroelectric are superior to $SiO_2$and S $i_3$ $N_4$. Ferroelctric increases on-current, decreases thresh old voltage of TFT and also improves breakdown characteristics. The a-SiN:H has optical band gap of 2.61 eV, refractive index of 1.8~2.0 and resistivity of 10$^{13}$ - 10$^{15}$ $\Omega$cm, respectively. Insulating characteristics of ferroelectrics are excellent because dielectric constant of ferroelectric is about 60~100 and breakdown strength is over 1MV/cm. TFT using ferroelectric has channel length of 8~20${\mu}{\textrm}{m}$ and channel width of 80~200${\mu}{\textrm}{m}$. And it shows that drain current is 3.4$mutextrm{A}$ at 20 gate voltage, $I_{on}$ / $I_{off}$ is a ratio of 10$^{5}$ - 10$^{8}$ and $V_{th}$ is 4~5 volts, respectively. In the case of TFT without ferroelectric, it indicates that the drain current is 1.5 $mutextrm{A}$ at 20 gate voltage and $V_{th}$ is 5~6 volts. With the improvement of the ferroelectric thin film properties, the performance of TFT using this ferroelectric has advanced as a gate insulator fabrication technology is realized.zed.d.

• Korean Journal of Materials Research
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• v.25 no.3
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• pp.138-143
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• 2015

Aluminum nitride, a compound semiconductor, has a Wurtzite structure; good material properties such as high thermal conductivity, great electric conductivity, high dielectric breakdown strength, a wide energy band gap (6.2eV), a fast elastic wave speed; and excellent in thermal and chemical stability. Furthermore, the thermal expansion coefficient of the aluminum nitride is similar to those of Si and GaAs. Due to these characteristics, aluminum nitride can be applied to electric packaging components, dielectric materials, SAW (surface acoustic wave) devices, and photoelectric devices. In this study, we surveyed the crystallization and preferred orientation of AlN thin films with an X-ray diffractometer. To fabricate the AlN thin film, we used the magnetron sputtering method with $N_2$, NH3 and Ar. According to an increase in the partial pressures of $N_2$ and $NH_3$, Al was nitrified and deposited onto a substrate in a molecular form. When AlN was fabricated with $N_2$, it showed a c-axis orientation and tended toward a high orientation with an increase in the temperature. On the other hand, when AlN was fabricated with $NH_3$, it showed a-axis orientation. This result is coincident with the proposed mechanism. We fabricated AlN thin films with an a-axis orientation by controlling the sputtering electric power, $NH_3$ pressure, deposition speed, and substrate temperature. According to the proposed mechanism, we also fabricated AlN thin films which demonstrated high a-axis and c-axis orientations.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.1
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• pp.63-70
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• 2023

Today, the importance of power semiconductors continues to increase due to serious environmental pollution and the importance of energy. Particularly, SiC-MOSFET, which is one of the wide bandgap (WBG) devices, has excellent high voltage characteristics and is very important. However, since the electrical properties of SiC-MOSFET are heatsensitive, thermal management through a package is necessary. In this paper, we propose an insulated metal substrate (IMS) method rather than a direct bonded copper (DBC) substrate method used in conventional power semiconductors. IMS is easier to process than DBC and has a high coefficient of thermal expansion (CTE), which is excellent in terms of cost and reliability. Although the thermal conductivity of the dielectric film, which is an insulating layer of IMS, is low, the low thermal conductivity can be sufficiently overcome by allowing a process to be very thin. Electric-thermal co-simulation was carried out in this study to confirm this, and DBC substrate and IMS were manufactured and experimented for verification.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.2
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• pp.125-128
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• 2023

Recently, as the process of the MOS device becomes more detailed, and the degree of integration thereof increases, many problems such as leakage current due to an increase in electron tunneling due to the thickness of SiO₂ used as a gate oxide have occurred. In order to overcome the limitation of SiO₂, many studies have been conducted on HfO₂ that has a thermodynamic stability with silicon during processing, has a higher dielectric constant than SiO₂, and has an appropriate band gap. In this study, HfO₂, which is attracting attention in various fields, was doped with Al and the change in properties according to its concentration was studied. Al-doped HfO₂ thin film was deposited using Plasma Enhanced Atomic Layer Deposition (PEALD), and the structural and electrical characteristics of the fabricated MIM device were evaluated. The results of this study are expected to make an essential cornerstone in the future field of next-generation semiconductor device materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.161-161
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• 2009

Ion bombarded inorganic materials for LC alignment has been researched as it provides controllability in a nonstop process for producing high-resolution displays. Many optically transparent insulators such as $SiOx$ and a-C:H have been investigated as potential candidates for inorganic alignment materials. Even so, LC orientation on a new material with superior capacity is required to produce high-performance displays. Many inorganic materials with high permittivities can reduce the voltage losses due to the LC alignment layer that are a trade-off for its capacitance. The minimum voltage for device operation can be applied to the LC under low external voltage using these materials. This means that low power consumption for LCD applications can be achieved using a high-k alignment structure in which the LC can be driven effectively with a low threshold voltage. Among the many other potential high-k oxides, HfO2 is considered to be one of the most promising due to its remarkable properties of high dielectric constant, relatively low leakage current, large band gap (5.68 eV), and high transparency. Due to these characteristics, HfO2 can be used in LC alignment to increase the capacitance of the inorganic alignment layer for low-voltage driving of LCs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.408-409
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• 2009

The memory characteristics of charge trap memory capacitor with high-k materials were investigated. I-V characteristics of the fabricated device with band gap engineered tunneling gate stacks consisted of $SiO_2$, $ZrO_2$, $Al_2O_3$ dielectrics were evaluated and compared with the one consisted of $SiO_2$ tunneling dielectric. The memory capacitor including engineered tunneling dielectrics of ($Al_2O_3/ZrO_2/SiO_2$) shows the fastest PIE speed and long data retention time.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.364.2-364.2
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• 2014

Magnesium oxide (MgO) thin films have attracted great scientific and technological interest in recent decades. Because of its distinguished properties such as a wide band gap (7.2 eV), a low dielectric constant (9.8), a low refractive index, an excellent chemical, and thermal stability (melting point=$2900^{\circ}C$), it is widely used as inorganic material in diverse areas such as fire resistant construction materials, optical materials, protective layers in plasma display panels, buffer layers of multilayer electronic/photonic devices, and perovskite ferroelectric thin films. Precursor used in the ALD requires volatility, stability, and low deposition temperature. Precursors using a heteroleptic ligands with different reactivity have advantage of selective reaction of the heteroleptic ligands on substrate during ALD process. In this study, we have synethesized new heteroleptic magnesium precursors ${\beta}$-diketonate and aminoalkoxide which have been widely used for the development of precursor because of the excellent volatility, chelating effects by increasing the coordination number of the metal, and advantages to synthesize a single precursor. A newly-synthesized Mg(II) precursor was adopted for growing MgO thin films using ALD.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.63-64
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• 2015

In this paper, a microstrip array antenna capacitively coupled to a microstrip line is studied. The array antenna consists of uniformly spaced rectangular microstrip patches arranged close to a feeding microstrip line on a grounded dielectric substrate. The effects of various parameters, such as strip width and length, distance between adjacent patches, gap between strip patches and microstrip feed line, on the antenna performance were examined. By properly adjusting geometrical parameters, the array suitable for a high gain antenna for use in a frequency band centered at 12.5 GHz was designed.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.6
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• pp.627-634
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• 2018

Gallium-based liquid metal, e.g., eutectic gallium-indium (EGaIn), is highly attractive as an electrode material for flexible and stretchable devices. On the liquid metal, oxide layer is spontaneously formed, which has a wide band-gap, and therefore is electrically insulating. In this paper, we fabricate a capacitor based on eutectic gallium-indium (EGaIn) liquid metal and investigate its cyclic voltammetry (CV) behavior. The EGaIn capacitor is composed of two EGaIn electrodes and electrolyte. CV curves reveal that the EGaIn capacitor shows the behavior of electric double-layer capacitors (EDLC), where the oxide layers on the EGaIn electrodes serves as the dielectric layer of EDLC. The oxide thicker than the spontaneously-formed native oxide decreases the capacitance of the EGaIn capacitor, due to increased voltage loss across the oxide layer. The EGaIn capacitor without oxide layer exhibits unstable CV curves during the repeated cycles, where self-repair characteristic of the oxide was observed. Finally, the electrolyte concentration is optimized by comparing the CV curves at various electrolyte concentrations.

• Journal of IKEEE
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• v.7 no.2 s.13
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• pp.223-229
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• 2003

In this thesis, the characteristics of an inverted-F antenna for the 2.4GHz and 5.8GHz zwirless local area network(WLAN) have been analysed in terms of the variation of design parameters. The antenna can be integrated on WLAN for notebook printed circuit board, and the characteristics in terms of the variation of the gap between feed line and shorting stub, gap between antenna's leg and ground plane, antenna leg's width, substrate's height and dielectric constant are analysed. By using these characterization plot of design parameter, the tuning techniques are proposed to design optimum antenna. The designed antenna has 170MHz, 500MHz frequency bandwidth ,VSWR is 1.6, 1.14 and 3.5dBi gain.