• Advances in nano research
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• v.2 no.4
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• pp.211-217
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• 2014

The self-assembled strain-induced sub-micrometric islands and nanostructures are grown from In-As-Sb-P quaternary liquid phase on InAs (100) substrates in Stranski-Krastanow growth mode. Two samples are under consideration. The first sample consists of unencapsulated islands and lens-shape quantum dots (QDs) grown from expressly inhomogeneous liquid phase. The second sample is an n-InAs/p-InAsSbP heterostructure with QDs embedded in the p-n junction interface. The morphology, size and shape of the structures are investigated by high-resolution scanning electron (SEM) and transmission electron (TEM) microscopy. It is shown that islands, as they decrease in size, undergo shape transitions. Particularly, as the volume decreases, the following succession of shape transitions are detected: sub-micrometric truncated pyramid, {111} facetted pyramid, {111} and partially {105} facetted pyramid, completely unfacetted "pre-pyramid", hemisphere, lens-shaped QD, which then evolves again to nano-pyramid. A critical size of $5{\pm}2nm$ for the shape transformation of InAsSbP-based lens-shaped QD to nano-pyramid is experimentally measured and theoretically evaluated.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.17-23
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• 2018

Recently, electric semiconductors became an issue because of efficient use of energy and compaction of electronics. Silicon electric semiconductors are difficult to put into it because of its physical limitations. Hence, the study of WBG (Wideband Gap) semiconductors like SiC and GaN began. These devices received attention because it can be miniaturized and worked at high temperatures over $300^{\circ}C$. WBG MOSFET electric semiconductors can show performance like silicon IGBT. This can solve the current problem of IGBT tail. The current study shows the technical principles and issues related to SiC and GaN power semiconductors. WBG devices can achieve high performance compared to silicon, but its performance can't be fully utilized because of lack in bonding technology. Therefore, this review introduces research on WBG devices and their packaging issues.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.390-392
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• 2013

The research was observed the characteristic of ZnO based oxide semiconductors for the transparent conducting display. The optical-physical properties of ZnO based oxide semiconductors) grown on p-Si wafer were presented. ZnO based oxide semiconductors was prepared by the RF magnetron sputtering system. The characteristic of ZnO based oxide semiconductorswas strongly influenced by the amount of localized electron state by the defects. The PL spectra moved to long wave number with increasing the defects in the film. The mobility of a-IGZO film was increased with increasing the oxygen gas flow rate. The resistivity of ZnO based oxide semiconductors was also related to the mobility of ZnO based oxide semiconductors, and the mobility increased at the sample with low resistivity. The electric characteristic of a-IGZO TFTs showed that it is an n-type semiconductor.

• Journal of the Korean Physical Society
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• v.73 no.12
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• pp.1884-1888
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• 2018

We have employed electron paramagnetic resonance spectroscopy and magnetization measurements in order to study the effect of Al-incorporation on the magnetic interactions in ZnO:Mn diluted magnetic semiconductors. Al-doping is shown to decrease the antiferromagnetic correlation and to increase the ferromagnetic interaction, which is attributed to the hydrogen-mediated ferromagnetic Mn complexes in our Mn-doped ZnO samples.

• Journal of Sensor Science and Technology
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• v.32 no.6
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• pp.391-402
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• 2023

Low-dimensional (zero-dimensional (0-dim), 2-dimensional (2-dim)) nanoparticles, such as chalcogenide compound semiconductors, III-V semiconductors, transition metal dichalcogenides (TMDs), II-VI semiconductors, nanocarbons, hybrid quantum dots (QDs), and perovskite QDs (PQDs), for which blue light emission has been observed, are reviewed. Current synthesis and device fabrication technologies as well as their prospective applications on next-generation quantum-dot-based light-emitting diodes are discussed.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.31-35
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• 2001

IGCTs have established themselves as the power semiconductor of choice at medium voltage levels within the last few years because of their low conduction and switching losses. The trade-off between these losses can be adjusted by various lifetime control techniques and the growing demand for these devices is driving the need for standard types to cover such applications as Static Circuit Breakers (low on-state) and Medium Voltage Drives (low switching losses). The additional demands of Traction (low operating temperatures) and Current Source Inverters (symmetric blocking) would normally result in conflicting demands on the semiconductor. This paper will outline how a range of power devices can meet these needs with a limited number of wafers and gate units. Some of the key differences between IGCTs and IGBTs will be explained and the outlook for device improvements will be discussed.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.19-19
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• 2003

The injection of spins into nonmagnetic semiconductors has recently attracted great interest due to the potential to create new classes of spin-dependent electronic devices. A recent strategy to achieve control over the spin degree of freedom is based on dilute ferromagnetic semiconductors. Ferromagnetism has been reported in various semiconductor groups including II-Ⅵ, III-V, IV and II-IV,-V$_2$, which will be reviewed. On the other hand, to date the low solubility of magnetic ions in non-magnetic semiconductor hosts and/or low Curie temperature have limited the opportunities. Therefore the search for other promising ferromagnetic semiconducting materials, with high magnetic moments and high Curie temperatures (Tc), is of the utmost importance. In this talk, we also introduce new pure ferromagnetic semiconductors, MnGeP$_2$ and MnGeAs$_2$, exhibiting ferromagnetism and a magnetic moment per Mn at 5K larger than 2.40 ${\mu}$B. The calculated electronic structures using the FLAPW method show an indirect energy gap of 0.24 and 0.06 eV, respectively. We have observed spin injection in MnGeP$_2$ and MnGeAs$_2$ magnetic tunnel junctions through semiconducting barriers.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.161-163
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• 2016

Organic semiconductors, in contrast with inorganic semiconductors, have DOS of the Gaussian distribution function which leads to difficulties to obtain the electron density with a closed equation. For this reason, the prediction of the device operation is extremely difficult in the development of OLED and the repetitive trial-and-error is required to find the appropriate electrical and optical properties of the devices. In this paper, the standard to analyze organic semiconductor is proposed by the optimization of the time and the accuracy which is necessary for the numerical calculation of the electron density in organic semiconductors.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.3
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• pp.215-222
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• 2022

Artificial neuromorphic devices are considered the key component in realizing energy-efficient and brain-inspired computing systems. For the artificial neuromorphic devices, various material candidates and device architectures have been reported, including two-dimensional materials, metal-oxide semiconductors, organic semiconductors, and halide perovskite materials. In addition to conventional electrical neuromorphic devices, optoelectronic neuromorphic devices, which operate under a light stimulus, have received significant interest due to their potential advantages such as low power consumption, parallel processing, and high bandwidth. This article reviews the recent progress in optoelectronic neuromorphic devices using various active materials such as two-dimensional materials, metal-oxide semiconductors, organic semiconductors, and halide perovskites

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.5
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• pp.419-430
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• 2022

Defects in solids play a vital role on thermoelectric properties through the direct impacts of electronic band structure and electron/phonon transports, which can improve the electronic and thermal properties of a given thermoelectric semiconductor. Defects in semiconductors can be divided into four different types depending on their geometric dimensions, and thus understanding the effects on thermoelectric properties of each type is of a vital importance. This paper reviews the recent advances in the various thermoelectric semiconductors through defect engineering focusing on the charge carrier and phonon behaviors. First, we clarify and summarize each type of defects in thermoelectric semiconductors. Then, we review the recent achievements in thermoelectric properties by applying defect engineering when introducing defects into semiconductor lattices. This paper ends with a brief discussion on the challenges and future directions of defect engineering in the thermoelectric field.