• 한국재료학회지
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• 제7권2호
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• pp.107-113
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• 1997

플라즈마를 이용한 유기금속 화학증착법에 의해 $Pt/Ti/SiO_{2}/Si$기판위에 $SrBi_{2}Ta_{2}O_{9}(SBT)$박막이 제조되었다. X-ray회절패턴, 미세구조 및 조성분석으로부터 Sr과 Ta bubbling 온도는 $120^{\circ}C$로 고정되었으며 Bi bubbling온도가 변화되었다. Bi bubbling 온도 $130^{\circ}C$에서 얻어진 SBT 박막의 유전상수 및 유전손실은 100kHz에서 각각 150과 0.02이며 누설전류 밀도는 20kV/cm 에서 약 $1.0{\times}10^{-8}A/cm^2$이었다. 이 조건에서 얻어진 SBT박막의 누설전류 특성은 poole-Frenkel기구에 의해서 지배된다. $550^{\circ}C$에서 annealing된 SBT박막의 잔류분극($_{2}P_{r}$)은 $9{\mu}C/cm^2$이며 항전계는 70kV/cm이었다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권4호
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• pp.449-457
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• 2012

The program/erase (P/E) cyclic endurances including bias temperature instability (BTI) behaviors of Metal-$Al_2O_3$-Nitride-Oxide-Semiconductor (MANOS) memories are investigated in comparison with those of Semiconductor-Oxide-Nitride-Oxide-Semiconductor (SONOS) memories. In terms of BTI behaviors, the SONOS power-law exponent n is ~0.3 independent of the P/E cycle and the temperature in the case of programmed cell, and 0.36~0.66 sensitive to the temperature in case of erased cell. Physical mechanisms are observed with thermally activated $h^*$ diffusion-induced Si/$SiO_2$ interface trap ($N_{IT}$) curing and Poole-Frenkel emission of holes trapped in border trap in the bottom oxide ($N_{OT}$). In terms of the BTI behavior in MANOS memory cells, the power-law exponent is n=0.4~0.9 in the programmed cell and n=0.65~1.2 in the erased cell, which means that the power law is strong function of the number of P/E cycles, not of the temperature. Related mechanism is can be explained by the competition between the cycle-induced degradation of P/E efficiency and the temperature-controlled $h^*$ diffusion followed by $N_{IT}$ passivation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.795-797
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• 1998

A $BaTiO_3$, ferroelectric material, was mixed $SrTiO_3$, $(x)BaTiO_3-(1-x)SrTiO_3$($0.7{\leq}x{\leq}1$) ceramic capacitor with stable electrical properties in high voltage was fabricated. And microstructure, electrical property were investigated with $SrTiO_3$ mol ratio. The shrinkage, open porosity, sintering density were predominated at $9BaTiO_3-0.1SrTiO_3$. Increasing $SrTiO_3$ mol ratio, curie temperature was shifted at low temperature and maximum permittivity was increased. Also, $0.9BaTiO_3-0.1SrTiO_3$ was showed stable dielectric properties at $25{\sim}80[^{\circ}C]$. V-I properties of specimen were observed in the temperature range of $21{\sim}143[^{\circ}C]$, were divided into three regions. The region I below 10[kV/cm] was shown Ohmic conduction, the region II from 10 to 30[kV/cm] was explained by the Poole-Frenkel emission theory and the region III above 30[kV/cm] was analysed by the tunneling effect.

• 한국재료학회지
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• 제17권11호
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• pp.574-579
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• 2007

Amorphous $BaTi_4O_9$ ($BT_4$) film was deposited on Pt/Si substrate by RF magnetron sputter and their dielectric properties and electrical properties are investigated. A cross sectional SEM image and AFM image of the surface of the amorphous $BT_4$ film deposited at room temperature showed the film was grown well on the substrate. The amorphous $BT_4$ film had a large dielectric constant of 32, which is similar to that of the crystalline $BT_4$ film. The leakage current density of the $BT_4$ film was low and a Poole-Frenkel emission was suggested as the leakage current mechanism. A positive quadratic voltage coefficient of capacitance (VCC) was obtained for the $BT_4$ film with a thickness of <70 nm and it could be due to the free carrier relaxation. However, a negative quadratic VCC was obtained for the films with a thickness ${\geq}96nm$, possibly due to the dipolar relaxation. The 55 nm-thick $BT_4$ film had a high capacitance density of $5.1fF/{\mu}m^2$ with a low leakage current density of $11.6nA/cm^2$ at 2 V. Its quadratic and linear VCCs were $244ppm/V^2$ and -52 ppm/V, respectively, with a low temperature coefficient of capacitance of $961ppm/^{\circ}C$ at 100 kHz. These results confirmed the potential suitability of the amorphous $BT_4$ film for use as a high performance metal-insulator-metal (MIM) capacitor.

• 한국재료학회지
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• 제27권1호
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• pp.48-52
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• 2017

In this study, we used I-V spectroscopy, photoconductivity (PC) yield and internal photoemission (IPE) yield using IPE spectroscopy to characterize the Schottky barrier heights (SBH) at insulator-semiconductor interfaces of Pt/$HfO_2$/p-type Si metal-insulator-semiconductor (MIS) capacitors. The leakage current characteristics of the MIS capacitor were analyzed according to the J-V and C-V curves. The leakage current behavior of the capacitors, which depends on the applied electric field, can be described using the Poole-Frenkel (P-F) emission, trap assisted tunneling (TAT), and direct tunneling (DT) models. The leakage current transport mechanism is controlled by the trap level energy depth of $HfO_2$. In order to further study the SBH and the electronic tunneling mechanism, the internal photoemission (IPE) yield was measured and analyzed. We obtained the SBH values of the Pt/$HfO_2$/p-type Si for use in Fowler plots in the square and cubic root IPE yield spectra curves. At the Pt/$HfO_2$/p-type Si interface, the SBH difference, which depends on the electrical potential, is related to (1) the work function (WF) difference and between the Pt and p-type Si and (2) the sub-gap defect state features (density and energy) in the given dielectric.

• Transactions on Electrical and Electronic Materials
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• 제16권3호
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• pp.124-129
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• 2015

Organic electronics are the domain in which the components and circuits are made of organic materials. This new electronics help to realize electronic and optoelectronic devices on flexible substrates. In recent years, organic materials have replaced conventional semiconductors in many electronic components such as, organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic photovoltaic (OPVs). It is well known that organic light emitting diodes (OLEDs) have many advantages in comparison with inorganic light-emitting diodes LEDs. These advantages include the low price of manufacturing, large area of electroluminescent display, uniform emission and lower the requirement for power. The aim of this paper is to model polymer LEDs and OLEDs made with small molecules for studying the electrical and optical characteristics. The purpose of this modeling process is, to obtain information about the running of OLEDs, as well as, the injection and charge transport mechanisms. The first simulation structure used in this paper is a mono layer device; typically consisting of the poly (2-methoxy-5(2'-ethyl) hexoxy-phenylenevinylene) (MEH-PPV) polymer sandwiched between an anode with a high work function, usually an indium tin oxide (ITO) substrate, and a cathode with a relatively low work function, such as Al. Electrons will then be injected from the cathode and recombine with electron holes injected from the anode, emitting light. In the second structure, we replaced MEH-PPV by tris (8-hydroxyquinolinato) aluminum (Alq₃). This simulation uses, the Poole-Frenkel -like mobility model and the Langevin bimolecular recombination model as the transport and recombination mechanism. These models are enabled in ATLAS- SILVACO. To optimize OLED performance, we propose to change some parameters in this device, such as doping concentration, thickness and electrode materials.

• KIEE International Transactions on Electrophysics and Applications
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• 제12C권4호
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• pp.208-213
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• 2002

The present study describe the electrical performance of amorphous T $a_2$ $O_{5-X}$ fabricated on the buffer layers Ti and Ti $O_2$. T $a_2$ $O_{5-X}$ thin films were grown on the Ti and Ti $O_2$ layers as a capacitor layer using reactive sputtering method. The X-ray pattern analysis indicated that the two as-deposited films were amorphous and the amorphous state was kept stable on the RTA(rapid thermal annealing) at even $700^{\circ}C$. Measurements of dielectric properties of the reactive sputtered T $a_2$ $O_{5-X}$ thin films fabricated in two simple MIS(metal insulator semiconductor), structures, (Cu/T $a_2$ $O_{5}$ Ti/Si and CuT $a_2$ $O_{5}$ Ti $O_2$Si) show that the amorphous T $a_2$ $O_{5}$ grown on Ti showed high dielectric constant (23～39) and high leakage current density(10$^{-3}$ ～10$^{-4}$ (A/$\textrm{cm}^2$)), whereas relatively low dielectric constant (～15) and tow leakage current density(10$^{-9}$ ～10$^{-10}$ (A/$\textrm{cm}^2$)) were observed in the amorphous T $a_2$ $O_{5}$ deposited on the Ti $O_2$ layer. The electrical behaviors of the T $a_2$ $O^{5}$ thin films were attributed to the contribution of Ti- $O_2$ and the compositionally gradient Ta-Ti-0, being the low dielectric layer and high leakage current barrier. In additional, The T $a_2$ $O_{5}$ Ti $O_2$ thin films exhibited dominant conduction mechanism contributed by the Poole-Frenkel emission at high electric field. In the case of T $a_2$ $O_{5}$ Ti $O_2$ thin films were related to the diffusion of Ta, Ti and O, followed by the creation of vacancies, in the rapid thermal treated thin films.films.

• 한국재료학회지
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• 제18권4호
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• pp.169-174
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• 2008

The structural and electrical properties of amorphous $BaSm_2Ti_4O_{12}$ (BSmT) films on a $TiN/SiO_2/Si$ substrate deposited using a RF magnetron sputtering method were investigated. The deposition of BSmT films was carried out at $300^{\circ}C$ in a mixed oxygen and argon ($O_2$ : Ar = 1 : 4) atmosphere with a total pressure of 8.0 mTorr. In particular, a 45 nm-thick amorphous BSmT film exhibited a high capacitance density and low dissipation factor of $7.60\;fF/{\mu}m2$ and 1.3%, respectively, with a dielectric constant of 38 at 100 kHz. Its capacitance showed very little change, even in GHz ranges from 1.0 GHz to 6.0 GHz. The quality factor of the BSmT film was as high as 67 at 6 GHz. The leakage current density of the BSmT film was also very low, at approximately $5.11\;nA/cm^2$ at 2 V; its conduction mechanism was explained by the the Poole-Frenkel emission. The quadratic voltage coefficient of capacitance of the BSmT film was approximately $698\;ppm/V^2$, which is higher than the required value (<$100\;ppm/V^2$) for RF application. This could be reduced by improving the process condition. The temperature coefficient of capacitance of the film was low at nearly $296\;ppm/^{\circ}C$ at 100 kHz. Therefore, amorphous BSmT grown on a TiN substrate is a viable candidate material for a metal-insulator-metal capacitor.