• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1994.11a
• /
• pp.50-53
• /
• 1994

In this study. we report the properties of optically pumped stimulated emission at room temperature (RT) from column-III nitride semiconductors of GaN, GaInN, AlGaN/GaN double hetero-structure (DH) and AlGaN/GaInN DH which grown by low pressure metal-organic vapor phase epitaxy on sapphire substrate using an AIN buffer-layer. The peak wavelength of the stimulated emission at RT from AlGaN/GaN DH is 370nm and the threshold of excitation pumping power density (P$\_$th/) is about 89㎾/$\textrm{cm}^2$, and they from AlGaN/GaInN DH are 403nm and 130㎾/$\textrm{cm}^2$, respectively. The P$\_$th/ of AlGaN/GaN and AlGaN/GaInN DHs are lower than the bulk materials due to optical confinement within the active layers of GaN and GaInN. The optical gain and the polarization of stimulated emission characteristics are presented in this article.

• Journal of Surface Science and Engineering
• /
• v.40 no.3
• /
• pp.113-116
• /
• 2007

Titanium dioxide ($TiO_2$) films were deposited by RF reactive magnetron sputtering on non-alkali glass and single crystal MgO (100) substrate at substrate temperature of $400^{\circ}C$. Micro structures of $TiO_2$ films were investigated by XRD, FE-SEM, and Pole figure measurements. $TiO_2$ films deposited on glass substrate showed preferred orientation of anatase (101), whereas $TiO_2$ films deposited on the MgO single crystal substrate showed hetero-epitaxial anatase (100). $TiO_2$ film grown on MgO substrate showed higher photoctalytic activity than that of glass substrate.

• Proceedings of the KIEE Conference
• /
• 1988.07a
• /
• pp.796-798
• /
• 1988

Langmuir-Blodgett(LB) films of arachic acid and TCNQ(tetracyanoquinodimethane) were prepared in the sample of Al/LB film/Al type where Al are electrodes, and polarization in LB film and dipolar moment of molecules in the films were measured by themally stimulated current(TSC). It is ascertaind in our experiments that dipolar mament of $C_{12}$TCNQ molecule was about 13-15 debye and the moment was directed from the alkyle chain toward TCNQ. Generation of the open circuit voltage was investigated on the z-type and Hetero structure of LB films.

• Journal of the Optical Society of Korea
• /
• v.15 no.2
• /
• pp.124-127
• /
• 2011

Quantum dots were designed within a GRIN-SCH(Graded index - Separate confinement Heterostructure) heterostructure to create a high power InAlAs/AlGaAs laser diode. 808 nm light emission was with a quantum dot composition of In0.665Al0.335As and wetting layer composition of Al0.2Ga0.8As by LASTIP simulation software. Typical characteristics of GRIN structures such as high confinement ratios and Gaussian beam profiles were shown to still apply when quantum dots are used as the active media. With a dot density of 1.0x1011 dots/cm2, two quantum dot layers were found to be good enough for low threshold, high-power laser applications.

• Journal of the Korea Society of Computer and Information
• /
• v.5 no.4
• /
• pp.102-105
• /
• 2000

The self-aligned AICaAs/GaAs HBTs with the mesa-etched emitter showed severe degradation in current gain under stress. The cause was identified to be due to instability of the surface states on extrinsic base. In this paper the surface states were diminished by the hetero-passivation of the InGaP ledge emitter and the reliability was drastically improved. The activation energy of current gain degradation was extracted to be 1.97eV and MTTF to be 4.8$\times$108 at 14$0^{\circ}C$ which has satisfied MIL standards.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.21 no.5
• /
• pp.11-16
• /
• 1984

In this paper, the construction of the Liquid Phase Epitaxy system for fabricating III-V compound semiconductor devices and the method of growing AIGaAs/GaAs Double-Hetero-structure are discussed. The possibility of this Double-Heterostructure for the Light Emitting Diode is confirmed also.

• Journal of the Korean Chemical Society
• /
• v.37 no.1
• /
• pp.68-75
• /
• 1993

Various biological activities (enzyme inhibitory potency, lipoxygenase inhibition, tadpole narcosis, vapor toxicity and heat of vaporization) of molecules are correlated with molecular descriptors. The molecular descriptors used in this works are molecular connectivity index, Wiener distance index and ad hoc descriptor, which can encode information about branching, size, cyclization, unsaturation, hetero atom content and polarizability. It is found that calculated values from multiple regression equations are in a good agreement with experimental data on five biological activities of alcohol, ester and ketone compounds.

• Journal of the Korean Magnetic Resonance Society
• /
• v.23 no.2
• /
• pp.46-50
• /
• 2019

Spin orbit torque would be applied as the next generation of MRAM, so many researchers are interested in related field. To make a more efficient device, electric current should convert into spin current with high efficiency. Moreover, it becomes important to measure efficiency of spin orbit torque accurately. We measured spin torque FMR of W/CoFeB hetero structure system with direct current. The efficiencies of the damping like torque and field like torque were measured by using the linewidth and on-resonance field proportional to direct current. In addition, we analyzed that a quadratic shift of the on-response field was caused by the Joule heating.

• Electronics and Telecommunications Trends
• /
• v.38 no.6
• /
• pp.52-61
• /
• 2023

With semiconductor scaling approaching the physical limits, devices including CMOS (complementary metal-oxide-semiconductor) components have managed to overcome yet are currently struggling with several technical issues like short-channel effects. Evolving from the process node of 22 nm with FinFET (fin field effect transistor), state-of-the-art semiconductor technology has reached the 3 nm node with the GAA-FET (gate-all-around FET), which appropriately addresses the main issues of power, performance, and cost. Technical problems remain regarding the foundry of GAA-FET, and next-generation devices called post-GAA transistors have not yet been devised, except for the CFET (complementary FET). We introduce a CFET that spatially stacks p- and n-channel FETs on the same footprint and describe its structure and fabrication. Technical details like stacking of nanosheets, special spacers, hetero-epitaxy, and selective recess are more thoroughly reviewed than in similar articles on CFET fabrication.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.19 no.2
• /
• pp.176-180
• /
• 2006

[ $(Na_{0.5}Bi_{0.5})TiO_3$ ][NBT] thin films were prepared on a highly (100) oriented $LaNiO_3[LNO]$ by sol-gel process. X-ray diffraction patterns of the NBT films annealed above $600^{\circ}C$ for 5 minutes have confirmed a highly (100) oriented growth and pseudocubic structure (a=3.884${\AA}$). The (l00) orientation factor increased from 90 to $99\%$ with increasing soaking time from 5 to 60 minutes at $600^{\circ}C$. The NBT films ($600^{\circ}C$/5 min,) have a flat and dense microstructure with large columnar grains, and their grain size are about 44 nm. The Au/NBT/LNO/Si hetero structure sample show a ferroelectric properties.