• 전자공학회논문지A
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• 제32A권8호
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• pp.78-85
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• 1995

We fabricated the Pb$_{1-0.28{\alpha}}La_{0.28}TiO_{3}$ (PLT(28)) thin film successfully by using the sol-gel method and characterized it to evaluate its potential for being utilized as the capacitor dielectrics of ULSI DRAMs. In our sol-gel process, the acetates were used as the starting materials. Through the TGA-DTA analysis, we established the excellent fabrication conditions of the sol-gel method for the PLT(28) thin film. We obtained the dense and crack-free PLT(28) thin film of 100% perovskite phase by drying at 350$^{\circ}C$ after each coating and final annealing at 650$^{\circ}C$. Its electrical properties were measured from the planar capacitors fabricated on the Pt/Ti/SiO$_{2}$/Si substrate. By the P-E hysteresis measurement, its paraelectric phase was identified and its dielectric constant and leakage current density were measured as 936 and 1.1${\mu}A/cm^{2}$, respectively. Those electrical values indicate that the PLT(28) thin film is the most successful candidate for the capacitor dielectrics of ULSI DRAMs at the present.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.176-178
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• 2005

Ferroelectric $Bi_{3.25}Nd_{0.75}Ti_{3}O_{12}(BNdT)$ thin films were proposed for capacitor of FeRAM. The BNdT thin films were grown on Pt/Ti $SiO_2/P-Si(100)$ substrates by the RF magnetron sputtering deposition. The dielectric properties of the BNdT were investigated by varying deposition temperatures. Increasing deposition temperature, the (117) peak was increased. An increase of columnar and recrystalline structure of BNdT films with increasing deposition temperature was observed by the Field Emission Scanning Electron Microscopy(FE-SEM). The dielectric constant and dielectric loss of the BNdT thin films with deposition temperature of $600^{\circ}C$ were 319 and 0.05, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.394-397
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• 2001

In this paper, in-situ deposited $Ru/RuO_2$ bottom electrodes have been investigated as new bottom electrodes for PZT thin film capacitor application. As a comparison, structural and electrical properties of PZT thin films on Pt/Ti and $RuO_2$ bottom electrodes are also investigated. The use of $Ru/RuO_2$ hybrid electrodes showed better electrical properties in compression with $RuO_2$ bottom electrode. With increasing Ru electrode thickness, the PZT thin films showed preferred orientation along the (110) direction and and leakage current of PZT thin films were improved. The PZT thin films on Ru (100nm)/$RuO_2$ electrodes exhibited excellent ferroelectric properties such as remant polarization and coercive field of $7.2C/cm^2$ and 46.35 kV/cm, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.248-249
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• 2005

The tungsten bronze type of strontium barium niobate(SBN) thin film was synthesized by metal organic decomposion method for SBN stock solution and the SBN thin film process were deposited by spin-coating process on Pt-deposited si-wafer(100) by magnetron sputtering system. The thickness of SBN thin film was 150$\sim$200 nm and were optimized for rpm of spin-coater system. The structural variation of SBN thin film was studied by TG-DTA and XRD. The deposited SBN stock solution on annealing at $400\sim800^{\circ}C$ a pure tungsten bronze SBN phase and the corresponding average grain size about 500$\sim$1000 nm influenced by annealing temperature.

• 한국전기전자재료학회논문지
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• 제17권9호
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• pp.947-952
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• 2004

Tb-doped lead zirconate titanate(Pb(Zr$\_$0.6/,Ti$\_$0.4/)O$_3$; PZT) thin films on Pt(111)/Ti/SiO$_2$/Si(100) substrates were fabricated by the sol-gel method. The effect on the structural and electrical properties of films measured according to Tb content. The dielectric and ferroelectric properties of Tb-doped PZT thin films were altered significantly by Tb-doping. The PZT thin film with higher dielectric constant and improved leakage current characteristic was obtained by adding 0.3 mol% Tb. The relative dielectric constant and the dielectric loss of the 0.3 mol% Tb-doped PZT thin film were 1611 and 0.024, respectively. Typical value of the swichable remanent poaraization(2Pr) and the coercive filed of the PZT film capacitor for 0.3 mol% Tb-doped were 61.4 ${\mu}$C/cm$^2$ and 61.9 kV/cm, respectively. Tb-doped PZT thin films showed improved fatigue characteristics comparing to the undoped PZT thin film.

• 센서학회지
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• 제16권5호
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• pp.377-383
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• 2007

We describe the fabrication and characterization of a doubly clamped multi-walled carbon nanotube (MWNT). The device was assembled by an application of electric field in solution. The MWNT was clamped on end of metal trench electrodes in solution and deposited with additional platinum (Pt) on edge of electrode for firmly suspending the MWNT by focused ion beam (FIB). The MWNTs range of diameter and length were 100 to 150 nm and 1.5 to $2{\mu}m$, respectively. Electrical characteristics of fabricated devices were measured by I-V curve and impedance analysis. The mechanical deformation was observed by resistivity in high air pressure. Resonant frequency around 6.8 MHz was detected and resistivity was linearly varied according to the magnitude of air pressure. This device could have potential applications in nanoelectronics and various sensors.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.148-148
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• 2011

일반적으로 LED 제작에 사용되는 c-plane GaN는 c축 방향으로 발생하는 분극의 영향을 받게 된다. 분극은 LED내 양자우물의 밴드를 기울게 하여 그 결과 전자와 홀의 재결합 확률을 감소시켜 낮은 내부양자효율을 가지게 된다. 이러한 문제를 해결하기 위한 여러 가지 방법들이 제시되었는데 그 중에서도 특히 a-plane 혹은 m-plane면과 같은 무분극 면을 사용하는 GaN LED가 주목받고 있다. 그 이유는 무분극 면은 분극이 발생하는 c축과 수직이기 때문에 분극의 영향을 받지 않아 높은 내부 양자효율을 가질수 있다. 본 연구에서는 MOCVD 장비를 사용하여 2인치 r-plane 사파이어 기판위에 3um두께의 a-plane GaN을 성장하였다. 그위에 2um정도로 Si을 도핑하여 n-type GaN 형성한후 단일 양자우물, 그리고 Mg을 도핑하여 p-type GaN을 성장하였다. 장파장대역의 a-plane LED의 특성을 알아보기 위해서 양자우물 형성시 In의 조성비를 높였다. 일반적인 포토리소그래피 공정과 Dry etching 공정을 사용하여 메사구조를 형성하였으며 Ti/Al/Pt/Au와 Ni/Au를 각각 n-type과 p-type의 전극 물질로 사용하였다. 제작된 LED의 특성을 파악하기 위해서 인가전류를 0부터 100mA까지 출력 스펙트럼을 측정하였으며 orange대역의 파장을 갖는 LED를 얻었다. 인가전류별 Peak 파장의 변화와 반측폭의 변화를 파악하여 장파장 대역의 a-plane LED의 특성을 확인하였다.

• 센서학회지
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• 제27권1호
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• pp.1-5
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• 2018

Two-dimensional (2D) niobate-based nanosheets have attracted attention as high-k dielectric materials. We synthesized strontiumsubstituted calcium niobate ($Ca_{0.8}Sr_{1.2}Nb_3O_{10}$) nanosheets by a two-step cation exchange process from $KCa_{0.8}Sr_{1.2}Nb_3O_{10}$ ceramic. The $K^+$ ions were exchanged with $H^+$ ions, and then H+ ions were exchanged with tetrabutylammonium ($TBA^+$) cations. The $Ca_{0.8}Sr_{1.2}Nb_3O_{10}$ nanosheets were then exfoliated, decreasing the electrostatic interaction between each niobate layer. Furthermore, $Ca_2Nb_3O_{10}$ nanosheets were synthesized in same process for comparison. Each exfoliated nanosheet shows a single-crystal phase and has a lateral size of over 100 nm. The nanosheets were deposited on a $Pt/Ti/SiO_2/Si$ substrate by the electrophoretic deposition (EPD) method at 40 V, followed by ultraviolet irradiation of the films in order to remove the remaining $TBA^+$ ions. The $Ca_{0.8}Sr_{1.2}Nb_3O_{10}$ thin film exhibited twice the dielectric permittivity (~60) and lower dielectric loss than $Ca_2Nb_3O_{10}$ thin films.

• 한국전기전자재료학회논문지
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• 제19권11호
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• pp.1014-1019
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• 2006

The influence of the number of solution coatings on the densification of the PZT thick films was studied. PZT powder and PZT precursor solution was prepared by a sol-gel method and PZT thick films were fabricated by the screen-printing method on the alumina substrates. The powder and solution of composition were (A) PZT(80/20)/PZT(20/80), (B) PZT(70/30)/PZT(30/70) and (C) PZT(60/40)/PZT(40/60), (D) PZT(52/48)/PT. The coating and drying procedure was repeated 4 times. And then the PZT precursor solution was spin-coated on the PZT thick films. A concentration of a coating solution was 0.5 moth and the number of coating was repeated from 0 to 6. The porosity of the thick films was decreased with increasing the number of coatings and the PZT thick films with 6-times coated showed the dense microstructure and thickness of about $60{\mu}m$. A grain size was increased with increasing the coating number. All PZT thick films showed the typical XRD patterns of a typical perovskite polycrystalline structure. The relative dielectric constant of PZT thick films was improved 30-100% as the number of coatings.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.346-349
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• 2002

Ferroelectric $Bi_{4-x}Nd_{x}Ti_{3}O_{12}(BNdT)$ thin films with the composition(x=0.75) were prepared on $Pt/Ti/SiO_{2}/Si(100)$ substrate by metal-organic deposition. The films were annealed by various temperatures from 550 to $650^{\circ}C$ and then the electrical and structural characteristics of BNdT films were investigated for the application of FRAM. Electrical properties such as dielectirc constant, 2Pr and capacitance were quite dependent on the thermal heat treatment. The measured 2Pr value on the BNdT capacitor annealed at $650^{\circ}C$ was $56{\mu}C/cm^{2}$ at an applied voltage of 5V. In fatigue characteristics value remained costant up to $8{\times}10^{10}$ read/write switching cycles at a frequency of 1Mhz regardless of annealing temperatures.