• E2M - 전기 전자와 첨단 소재
• /
• 제8권4호
• /
• pp.443-450
• /
• 1995

A directional coupler which on the X-cut $LiNbO_3$ substrate is fabricated by using proton exchange method and self-aligned method. After proton exchange process, the waveguide is formed by annealing process. The relation ship between refractive index change of waveguide and maximum output was studied along with the annealing time. A self-aligned method was used to simplify the fabrication process of the waveguide and to maximize the efficiency of electric field. The on-off state of modulator has been observered with the switching of the directional coupler by the electric field effect and also the switching voltage of the directional coupler has been measured with 8.0 [V].

• 한국결정성장학회지
• /
• 제2권1호
• /
• pp.70-75
• /
• 1992

강유전 요업체내에 존재하는 잔류응력에 대한 모델이 제시되었다. 모델로부터 다음과 같은 두가기 사실을 알 수 있었다. 첫째 잔류응력은 입계와 분역경계에 존재하며, 입계에 존재하는 응력이 분역경계에 존재하는 응력보다 컸다. 둘째는 입자내에 분역이 존재할 때, 잔류응력은 입자크기가 증가함에 따라 감소했다. 위와 같은 사실은 ($PbZr_{0.4}Ti_{0.6}O_3$)요업체에서 분극에 의해 유발된 미세균열과 입자크기에 따른 승온과 냉각시 유전율차이로부터 증명되었다.

• E2M - 전기 전자와 첨단 소재
• /
• 제9권6호
• /
• 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.

• E2M - 전기 전자와 첨단 소재
• /
• 제9권6호
• /
• pp.558-563
• /
• 1996

We fabricated high voltage hydrogenerated amorphous silicon thin film transistors (a Si:H HVTFT) and investigated its temperature dependent characteristics of from 303 K to 363 K. The results show that the drain current was decreased at low gate voltage and increased at high gate voltage exponentially. According to the increasing the thickness of a Si layer, drain current increased. Difference of drain current at 363 K was increasd at the lower gate voltage and decreased at the higher gate voltage. When the drain and gate voltage of 100 V applied, the drain current increased linearly with rise temperature.

• Journal of Advanced Marine Engineering and Technology
• /
• 제30권8호
• /
• pp.927-933
• /
• 2006

The structural and electrical characteristics of PLZT thin films fabricated onto $Pt/IrO_2/Ir/Ti/SiO_2/Si$ substrates by a pulsed laser deposition were investigated to develop the high dielectric thin films for capacitor layer of semiconductor memory devices The slim region 14/50/50 PLZT thin films were fabricated by PLD and estimated the characteristics for memory application 14/50/50 PLZT thin films have crystallize into perovskite structure at the $600^{\circ}C$ deposition temperature, 200 mTorr of oxygen pressure, and 2 $J/cm^2$ of laser energy density. In this condition PLZT thin films had the dielectric constant as high as 985, storage charge density 8.17 ${\mu}C/cm^2$ and charging time 0.20 ns. Leakage current density was less than $10^{-10}A/cm^2$ up to 5 V bias voltage.

• 한국재료학회지
• /
• 제6권6호
• /
• pp.610-617
• /
• 1996

강유전체 재료의 하부전극으로 사용되고 있는 Pt/Ti 박막의 접착력에 대한 열처리 분위기의 영향을 연구하였다. 시편의 접착력은 90$^{\circ}$ 필 테스트 방법을 사용하여 정량적으로 측정하였다. 열처리 후 사용된 분이기에 관계없이 모두 접착력이 감소하였는데 특히 산소분위기에서 열처리 한 시편의 접착력이 매우 크게 감소하였다. AES depth profile과 단면 TEM을 이용하여 계면반응을 관찰한 결과 산소열처리시에는 Ti가 외부에서 확산해 온 산소와 반응하여 rutile TiO2상이 형성됨을 알 수 있었다. 그러므로 산소열처리 후에 일어나는 접착력의 급격한 감소 원인은 열처리시 취약한 TiO2상이 형성되며 이로 인해 Ti 접착층이 고갈되기 때문임을 알 수 있었다.

• 한국세라믹학회지
• /
• 제51권6호
• /
• pp.591-597
• /
• 2014

A poled lead zirconate titanate (PZT) rectangular parallelepiped specimen was subjected to through-thickness electric fields at five loading rates and four temperatures. The rates of the electric field were 0.01, 0.10, 0.25, 0.50, and $1.00MVm^{-1}s^{-1}$; the temperatures were 20, 50, 80, and $110^{\circ}C$. From the measured polarization hysteresis responses, the so-called reference remnant polarization and strains were calculated. Using the calculated reference remnant polarization hysteresis loops, the effects of loading rates and temperature were discussed; using the calculated reference remnant strains, strain butterfly loops were calculated and compared with observations.

• Transactions on Electrical and Electronic Materials
• /
• 제17권1호
• /
• pp.29-32
• /
• 2016

Using the various exchange-correlation functionals, such as LDA, GGA-PBE, GGA-PBEsol and GGA-AM05 functionals, first principle studies were conducted to determine the structures of paraelectric and ferroelectric PbTiO₃. Based on the structures determined by the various functionals, the piezoelectric properties of PbTiO₃ are predicted under the density-functional perturbation theory (DFPT). The present prediction with the various GGA functionals are closer to the experimental findings compared to the LDA values. The present DFT calculations using the GGA-PBEsol functional estimate the experimental data more reasonably than the conventional LDA and GGA fucntionals. The GGA-AM05 functional also predicts the experimental data as well as the GGA-PBEsol. The piezoelectric tensor calculated with PBEsol is relatively insensitive to pressure.

• E2M - 전기 전자와 첨단 소재
• /
• 제8권5호
• /
• pp.648-657
• /
• 1995

정보처리의 다양화, 고속화를 위하여 장래의 집적회로는 다량의 정보를 단시간에 처리하지 않으면 안된다. 종래, 3년에 4배의 고집적화가 실현되어 LSI개발에 기술 견인차의 역할을 하고 있는 DRAM(Dynamic Random Access Memory)은 미세화기술의 한계를 우려하면서도 오히려 개발에 박차를 가하고 있다. 이러한 DRAM의 미세, 대용량화에는 미세가공 기술, 새로운 메모리 셀과 트랜지스터 기술, 새로운 회로 기술, 그 이외에 재료박막기술, Computer aided design/Design automation(CAD/DA) 기술, 검사평가기술 혹은 소형팩키지(package)기술등의 광범위한 기술발전이 뒷받침되어 왔다. 그 중에서 미세가공 기술 및 새로운 트랜지스터 기술과 메모리 셀 기술을 중심으로 개발 동향을 살펴보고 최근에 발표된 1Gbit DRAM의 시제품 기술에 대하여 분석해 보기로 한다.

• E2M - 전기 전자와 첨단 소재
• /
• 제10권2호
• /
• pp.156-165
• /
• 1997

D-E hysteresis loops have been measured for the 65/35 mole % copolymer of vinylidene fluoride and trifluoroethylene over wide temperature range. The remanent polarization and the coercive field at room temperature were estimated to be 75 mC/m$^{2}$ and 55 MV/m respectively. D-E hysteresis loops were observed even below the glass transition temperature(-20.deg. C) and the remanent polarization and the coercive field were larger, as the temperature lower. It seems that the remanent polarization and the coercive field depend on the amorphous region as well as crystalline region in this copolymer. And the ferroelectric-to-paraelectric phase transition was observed at 90.deg. C on heating and 80'C on cooling. Double hysteresis loops were observed at the temperature(85.deg. C) of paraelectric phase.