• Transactions on Electrical and Electronic Materials
• /
• 제5권1호
• /
• pp.24-28
• /
• 2004

We have used ITO/Alq$_3$/Al structure to study electrical conduction mechanism in organic light-emitting diodes. Current-voltage-luminance characteristics were measured at room temperature by varying the thickness of Alq$_3$ layer from 60 to 400mm. We were able to confirm that there are three different mechanisms depending on the applied voltage region; ohmic, space-charge-limited current, and trap-charge-limit-current mechanism. And the maximum luminous efficiency was obtained when the thickness of Alq$_3$ layer is 200nm.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 추계학술대회 논문집
• /
• pp.480-483
• /
• 2000

Polyimide is a well-known organic dielectric material, which has not only high chemical and thermal stability but also good electrical insulating and mechanical properties. In this research, the electrical properties of PI LB films were investigated at room temperature. At low electric field, ohmic conduction(I∝V) was observed and the calculated electrical conductivity was about 9.7$\times$10$^{-15}$ S/cm. At high electric field, conduction(I∝V$^2$) was observed and the conduction mechanism was explained by space charge limited region effect. The dielectric constant of LB film was about 7.5.

• 한국가스학회지
• /
• 제28권1호
• /
• pp.65-72
• /
• 2024

재생에너지 자원이 풍부한 제주도에서 수전해 시스템을 활용하여 그린수소를 생산하는 실증단지를 준비 중이며, 수전해 시스템의 장기 운영시 상황을 검토하기 위하여, PEM 수전해 셀을 가속시험평가 하여 수전해 셀의 내구성을 검토하였고, 제주도 풍력기반의 전력패턴을 적용하였을 때 수전해 셀의 내구성을 검토하였다. 가속시험평가 (저전류-고전류 반복 인가)를 800시간 진행한 후, PEM 수전해 셀의 성능이 최대 10%, 운전조건에서 5.5% 감소되었으며, 임피던스 분석결과 PEM 수전해 셀의 Ohmic 저항보다 전극의 분극저항이 크게 증가한 것을 확인할 수 있다. 그리고 제주도의 풍력패턴을 적용하여 내구성평가를 진행한 경우, PEM 수전해 셀의 성능이 최대 1.6%, 운전 조건에서 1% 미만의 성능감소를 보여주었으며, 임피던스 결과 Ohmic 저항 및 전극의 분극저항의 변화가 작은 것을 알 수 있다.

• 한국산학기술학회논문지
• /
• 제19권8호
• /
• pp.14-18
• /
• 2018

일반적으로 반도체소자의 이동도를 높이기 위하여 반도체소자에서 옴접촉이 중요하게 다루어진다. 반도체 구조의 PN접합은 공핍층을 포함하고 있으며, 공핍층은 전기적인 비선형을 유도하고 쇼키접압을 만들어내는 반도체 고유의 물리적인 특징이다. 본 연구에서는 절연막이 전도성에 미치는 효과를 조사하기 위해서 $SiO_2$ 박막과 $V_2O_5/SiO_2$ 박막의 전기적인 특성을 비교하여 조사하였다. 미소전계영역에서 $SiO_2$ 절연막의 전기적인 특성으로부터 비선형 쇼키접합을 이루고 있는 것을 확인하였으며, 그 위에 증착된 $V_2O_5$ 박막은 오믹특성을 갖는 것을 확인하였다. 절연막의 PN 접합에 의한 쇼키접합 특성이 누설전류를 차단하여 $V_2O_5$ 박막의 전도성을 우수하게 만들었다. 양의 전압에서 $SiO_2$ 박막의 커패시턴스 값은 매우 낮았으나 $V_2O_5$ 박막의 커패시턴스 값은 전압이 증가할수록 증가하였다. 일반적인 전계영역에서 $SiO_2$ 박막의 절연 효과에 의해 $V_2O_5$ 박막의 전도성이 증가하는 것을 확인하였다. 절연박막은 공핍층의 효과를 이용하는 쇼키접합을 갖게 되며, 반도체에서의 쇼키접합은 전도성을 높이는 효과가 있는 것을 확인하였다.

• KIEE International Transactions on Electrophysics and Applications
• /
• 제11C권4호
• /
• pp.99-106
• /
• 2001

An overview of Silicon Carbide (SiC) Static Induction Transistor (SIT) development is presented. Basic conduction mechanisms are introduced and discussed, including ohmic, exponential, and space charge limited conduction (SCLC) mechanisms. Additionally, the impact of velocity saturation and temperature effects on SCLC are reviewed. The small-signal model, breakdown voltage, power density, and different gate structures are also discussed, before a final review of published SiC SIT results. Published S-band (3-4 GHz) results include 9.5 dB of gain and output power of 120 W, and L-band (1.3 GHz) results include 400 W output power, 7.7 dB of gain, and power density of 16.7 W/cm.

• 전기학회논문지
• /
• 제56권10호
• /
• pp.1786-1790
• /
• 2007

The $(SrCa)TiO_3(SCT)$ thin films are deposited on Pt-coated electrode ($Pt/TiN/SiO_2/Si$) using RF sputtering method at various deposition temperature. The dielectric constant of SCT thin films were increased with the increase of deposition temperature, and changed almost linearly in temperature ranges of $-80{\sim}+90[^{\circ}C]$. Also, SCT thin films was observed the phenomena of dielectric relaxation with the increase of frequency, and the relaxation frequency was observed above 200[kHz]. V-I characteristics of SCT thin films show the increasing leakage current with the increases of deposition temperature. The conduction mechanism of the SCT thin films observed in the temperature range of $25{\sim}100[^{\circ}C]$ can be divided into three characteristic regions with different mechanism by the increasing current. The region 1 below 0.8[MV/cm] shows the ohmic conduction. The region 2 can be explained by the Child's law, and the region 3 is dominated by the tunneling effect.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1997년도 추계학술대회 논문집
• /
• pp.5-8
• /
• 1997

A study on the electrical conduction characteristics of the ultrathin organic films is one of the important factors for the development of molecular electronic devices. The Langmuir- Blodgett(LB) technique has recently been attracted interest as a method of the deposition ultrathin films. We hate fabricated N-docosyl N\`-methyl viologen-diTCNQ(DMVT) anion radical LB film and investigated the molecular orientation and electrical conduction characteristics. We have measured infrared transmission-reflection spectra. The alkyl chain is found to he well-ordered with the tilt angle of 13$^{\circ}$ with respect to the substrate surface normal and the TCNQ plane is tilted at 76$^{\circ}$ the surface normal. In ESR spectrum, we confirmed that a half-amplitude linewidth is clearly dependent on the incident angle, which indicates conducting species change. The in-plane conductivity of 31 lagers is approximately 1.33$\times$10$^{-6}$ S/cm. The ohmic behaviour was observed below 0.6 V, when current-voltage(I-V) characteristics was measured verically.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1992년도 하계학술대회 논문집 B
• /
• pp.918-921
• /
• 1992

A basic study on the discharge phenomenum of rod-to-rod microgap in the deionized water has been investigated with emphasis on the microgap spacing. The I-V charateristics for the case of ac and dc applied voltages had 3 different regions, a low conduction ohmic region, a medium conduction corona discharge region, and a high conduction arc discharge region. The corona discharge in the deionized water for the case of ac and de applied voltages had no different from the those in the air. But the arc discharge in the water occurred pulsative with sound which, however it is not clear, would be encounted due to the influences from the low temperature of the ambient water, vast of electrolytic generated electronegative gases(e.g. $O_2$, OH, O) and water molecules($H_2O$), and the space charge effects near the rod in the microgap from the ions of $H^+$, $OH^-$, $O_2^-$, etc, whose mobilities in the water are originally very low.

• E2M - 전기 전자와 첨단 소재
• /
• 제11권10호
• /
• pp.60-65
• /
• 1998

Deposition conditions, surface morphology, and electrical properties of polyamic acid alkylamine salts (PAAS) Langmuir-Blodgett(LB) films have been investigated through a study of surface pressure-area $\pi$-A isotherms, AFM (atomic force microscopy), and current-voltage characteristics. To obtain the optimum conditions of film deposition, the $\pi$-A isotherms were examined by varying temperature, barrier moving speed, dipping speed, spreading amount of solution etc. The Z-type LB films were made at the surface pressure of 5 mN m-1 and 25 mN m-1 for the AFM study; the former surface pressure forms the gas phase and the latter one forms the solid phase. The LB film made in the gas phase show domains with a size of about 200 A diameter and 70 A height. However, the LB films made in the solid phase show a very smooth surface with 2 A surface roughness. In the current-voltage characteristics measured along the perpendicular direction of the films, ohmic conduction has been observed below 105 V cm-1 and the calculated electrical conductivity is about 10-13 S cm-1. Nonohmic conduction has been observed above = 10-11 V cm and the conduction mechanism can be explained by the Schottky effect.

• 한국전기전자재료학회논문지
• /
• 제14권9호
• /
• pp.757-761
• /
• 2001

We studied emitting properties of organic electroluminescent devices fabricated using the spin-coating and Langmuir-Blodgett(LB) technique. The LB technique has the advantage of precise control of the thickness better than spin-coating method. LB monolayer of poly(3-hexylthiophene)(P3HT) was deposited 27 layers onto the indium-tin-oxide(ITO) substrate as Y-type films by the vertical dipping method. In the absorption spectra, the λ$\_$max/ of P3HT-AA LB films and of spin-coating films showed about at 510, 545 and 590 nm corresponding to 2.43, 2.28, 2.10eV. And we observed that the turn-on voltage of devices deposited by LB method(10V) was higher than that of spin-coating method(8.5V) in voltage-current-luminance characteristic. In the logV-logJ characteristics of ITO/P3HT-AA LB/Al device, we confirmed that El device fabricated by LB method follows three conduction mechanisms: ohmic, space-charge-limited current(SCLC) conduction and trapped-carrier-limited space-charge current(TCLC) conduction.