• Korean Management Science Review
• /
• v.18 no.1
• /
• pp.155-164
• /
• 2001

The widespread diffusion of Internet has enables every college and education institute to develope cyber education systems to meet the multiple needs of students, but it is not true that the effectiveness of cyber education is fruitful in terms of evaluation systems. Most of the early developed web-based evaluation systems for cyber education require that all the students should solve uniformed test set which are included in the predetermined static HTML pages. Therefore, it is impossible to dynamically provide a test set with consistency and reliability. This paper purpose to describe the employment of simulated annealing in cyber testbank system for test set generation that satisfy all constraints. The constraints include number of items for each skill, method, domain, topic, and so on. This research developed two phase heuristic combining sequential test set generation algorithm with simulated annealing. As a result of computer simulations, it was found that the two phase heuristic outperforms the other algorithms.

• Electrical & Electronic Materials
• /
• v.9 no.6
• /
• pp.584-592
• /
• 1996

Coupling optical modulator which on the $LiTaO_3$ substrate is fabricated by using proton exchange method and self-aligned method. Proton exchange of proton diffusion method was applied to pattern a waveguide on $LiTaO_3$ substrate. The annealing at >$400^{\circ}C$ was carded out to control waveguide width and depth. The depths of the two annealed optical waveguides, which were measured by using .alpha.-step, were 1.435 K.angs. and 1.380 K.angs. Using .alpha.-step facility, we examined that the width of waveguides is increased from 5.mu.m to 6.45 .mu.m and 6.3.mu.m due to the annealing effects. The process of proton exchange was done at 150.deg. C for 120 min, >$200^{\circ}C$ for 60 min and annealing process was done at >$400^{\circ}C$ for 90 min, >$400^{\circ}C$ for 60 min. The high speed coupling optical modulator has very good figures of merits; the measured high frequency power were achieved.

• Proceedings of the KIEE Conference
• /
• 1997.07d
• /
• pp.1630-1632
• /
• 1997

We have investigated activation phenomena of implanted ions on silicon wafers using microwave(2.45GHz). It is found that the higher concentration of impurities makes the better activation effects by microwave annealing. We have exposed poly-Si TFTs by microwave in order to anneal and improved the device performance. Microwave activates source/drain ions and lowers the contact resistance so that the current of the poly-Si TFTs increases. In addition, the leakage current of hydrogen passivated poly-Si TFTs is decreased after microwave annealing, due to the diffusion of hydrogen ions and curing the defects in the poly-Si active channel.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07a
• /
• pp.41-43
• /
• 2004

Dielectric thin films of $(Pb_{0.72}La_{0.28})Ti_{0.93}O_3$ were deposited on $Pt(111)/Ti/SiO_2/Si$ substrates in situ by pulsed laser deposition(PLD) and annealed with different gases which are forming gas and oxygen gas, respectively. The diffusion of hydrogen into the ferroelectric film was caused by annealing process and resulted in the destruction of polarization. The dielectric properties of forming gas annealed PLT thin films, which are dielectric constant, ferroelectric characteristic, and leakage current characteristics, were degraded

• Journal of the Korean Vacuum Society
• /
• v.16 no.5
• /
• pp.343-347
• /
• 2007

Fe thin films exhibited (100) preferential orientation when they were deposited at low deposition rate of $0.1{\AA}/s$ on glass substrates by using facing target sputtering system. The (100) oriented Fe layer induces (100) orientation of Pt layer deposited on it owing to hetero-epitaxial growth. After annealing at $600^{\circ}C$ in $H_2$ atmosphere, FePt films exhibited f.c.t. (001) texture in the whole film caused by inter-diffusion between atoms. We have also confirmed that the homogeneously inter-diffused compositional modulation in the film after the annealing process. Furthermore, annealing process in $Ar+H_2$ atmosphere at $400^{\circ}C$ during Pt deposition was effective for attaining Pt (100) texture. The annealing process during Pt deposition also induced in low annealing temperature and decreased annealing time for attaining the FePt f.c.t. (001) structure.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2001.06a
• /
• pp.42-43
• /
• 2001

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1998.08a
• /
• pp.77.3-77
• /
• 1998

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.16 no.2
• /
• pp.179-184
• /
• 2016

In recent years, the on-resistance, power loss and cell density of Si power devices have not exhibited significant improvements, and performance is approaching the material limits. GaN is considered an attractive material for future high-power applications because of the wide band-gap, large breakdown field, high electron mobility, high switching speed and low on-resistance. Here we report on the Ohmic contact resistance and reverse-bias characteristics of AlGaN/GaN Schottky barrier diodes with and without annealing. Annealing in oxygen at $500^{\circ}C$ resulted in an increase in the breakdown voltage from 641 to 1,172 V for devices with an anode-cathode separation of $20{\mu}m$. However, these annealing conditions also resulted in an increase in the contact resistance of $0.183{\Omega}-mm$, which is attributed to oxidation of the metal contacts. Auger electron spectroscopy revealed diffusion of oxygen and Au into the AlGaN and GaN layers following annealing. The improved reverse-bias characteristics following annealing in oxygen are attributed to passivation of dangling bonds and plasma damage due to interactions between oxygen and GaN/AlGaN. Thermal annealing is therefore useful during the fabrication of high-voltage GaN devices, but the effects on the Ohmic contact resistance should be considered.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.11a
• /
• pp.17-18
• /
• 2006

고상 확산 방법을 이용하여 얕은 소스/드레인 접합을 가지는 SOI (Silicon-On-Insulator) MOSFET 소자를 제작하였다. 확산원으로는 PSG(Phosphorus silicate glass) 박막과 PBF(Poly Boron Film) 박막이 각각 n, p-type 소자 형성을 위해 사용되었다. 얕은 접합 형성을 위하여 급속 열처리 방법(RTA: Rapid Thermal Annealing)을 이용하여 PSG와 PBF로부터 인과 붕소를 SOI MOSFET 소자의 소스/드레인으로 확산시켰다. 또한, 소자 특성 개선을 위한 후 속 열처리 공정으로 희석된 수소 분위기 중에서 FA(Furnace Annealing)를 실시하였다. SPD 기술을 적용하여 10 nm 이하의 매우 얕은 p-n 접합을 형성할 수 있었고, 양호한 다이오드 특성을 얻을 수 있었다. 또한, SPD 방법으로 결함이 없는 접합 형성이 가능하며, 소자 제작 공정의 최적화를 통해 차세대 CMOS 소자로 기대되는 SOI MOSFET를 성공적으로 제작할 수 있었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.05a
• /
• pp.349-352
• /
• 2001

In this paper, novel device structure in order to realize ultra fast and ultra small silicon devices are investigated using ultra-high vacuum chemical vapor deposition(UHVCVD) and Excimer Laser Annealing (ELA) for ultra pn junction formation. Based on these fundamental technologies for the deep sub-micron device, high speed and low power devices can be fabricated. These junction formation technologies based on damage-free process for replacing of low energy ion implantation involve solid phase diffusion and vapor phase diffusion. As a result, ultra shallow junction depths by ELA are analyzed to 10~20 nm for arsenic dosage (2$\times$10$^{14}$ $\textrm{cm}^2$), excimer laser source(λ=248nm) is KrF, and sheet resistances are measured to 1k$\Omega$/$\square$ at junction depth of 15nm.