KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 6 of 6

Some of the metrics are blocked by your
consent settings
PMMA/High-k Self-assembled TiO2 /PMMA Multi-layer Gate Dielectric for P3HT Organic Field Effect Transistors
(2022-01-01)
Inpor, Kroekchai
;
Houngkamhang, Nongluck
;
Thanachayanont, Chanchana
;
Prichanont, Seeroong
;
Kayunkid, Navaphun
In this work, a multi-layer structure of poly (methyl methacrylate)/ titanium dioxide/poly (methyl methacrylate) (PMMA/TiO₂ /PMMA; PTP) was proposed as a top-gate insulator for P3HT-based organic field-effect transistors (OFETs). Adding a TiO₂ interlayer as a high dielectric constant (high-k) material into PMMA film enables the modification of the dielectric constant of the multi-layers PTP film. The content of TiO₂ in the PTP film, which can be varied by changing the number of soaking cycles in TiO₂ solution, plays a crucial rule in modifying the dielectric constant of the PTP film. The higher the TiO₂ content used in the PTP film, the higher the dielectric constant of PTP film can be obtained. However, using high TiO₂ content led to a reduction in the dielectric constant of the PTP film due to leakage current induced by the agglomeration of TiO₂. The utilization of the top-gate insulator containing TiO₂ significantly enhanced several P3HT-OFETs characteristics, e.g., an increase in the I<inf>on</inf>/I<inf>off</inf> ratio, and a decrease in the threshold voltage. However, the use of the PTP top-gate insulator with a high content of TiO₂ resulted in regressions in the OFETs characteristics, such as a decrease in carrier mobility and reduction in the I<inf>on</inf>/I<inf>off</inf> ratio. OFETs operating at the optimum conditions of the PTP gate-insulator, with PTP thickness of 225 nm and RMS roughness of 20.0 nm, provided a dielectric constant of 7.13, a threshold voltage of-8.49 V, a saturation mobility of 2.2× 10-4 cm²V-1s-1, I<inf>on</inf>/I<inf>off</inf> ratio of 37.9, and a subthreshold slope of 0.39 V/decade.
Some of the metrics are blocked by your
consent settings
Dielectric Constant Determination using Dual Doppler Modules
(2021-01-01)
Leekul, Prapan
;
Mgawe, Bonny
;
Kazema, Twahir
;
Dao, Hoang Nam
;
Sirisuk, Phaophak
This paper presents a dielectric constant determination system based on dual Doppler modules. The key principle is to assign two slightly different radio frequencies to each module. It is demonstrated that dielectric constant of a material under test can be determined from the measured reflection coefficient. The concept was validated at 10 GHz band by measuring reflected waves from various materials including soil with different moisture content. Results illustrated good agreement between measured results from the proposed sensor as compared with the literatures. The results confirm that the proposed technique is applicable for monitoring soil characteristics.
Some of the metrics are blocked by your
consent settings
Effect of hydrated salts on the microstructure and phase transformation of poly(vinylidenefluoride-hexafluoropropylene) composites
(2018-05-01)
Yuennan, Jureeporn
;
Sukwisute, Pisan
;
Muensit, Nantakan
The present work has investigated a means of fabricating porous, β phase P(VDF-HFP) film by adding two kinds of hydrated metal salts. Without the use of mechanical stretching or electrical poling treatments, MgCl<inf>2</inf> •6H<inf>2</inf>O and AlCl<inf>3</inf> •6H<inf>2</inf>O are found to induce the formation of β phase crystals in porous film derived from the solution casting method. Trivalent Al ions have been found to effectively promote the self-oriented β phase of the P(VDF-HFP) film greater than divalent Mg ions. The overall β content is achieved about 38% and 42% for adding 0.25 wt% Mg- and Al-salts, respectively. The average pore sizes and surface roughness of porous P(VDF-HFP) films are increased with increasing salt concentration. The dielectric constant of about 5 for pure P(VDF-HFP) film (at 100 Hz) has been boosted up to 13-19 when adding the salts. In addition, the P(VDF-HFP) films filled with Al-salt exhibit the largest piezoelectric coefficient of 20 pC/N. Thus, the modified polymers are one of candidate materials for using in dielectric and piezoelectric applications.
Some of the metrics are blocked by your
consent settings
Optimum conditions for fabrication high-density KNN-LS-BF ceramics by combustion method
(2013-12-01)
Panya, Peerapong
;
Wattanawikkam, Chakkaphan
;
Laowanidwatana, Artid
;
Vittayakorn, Naratip
;
Bongkarn, Theerachai
The 0.996(0.95K<inf>0.5</inf>Na<inf>0.5</inf>NbO<inf>3</inf>-0.05LiSbO <inf>3</inf>)-0.004BiFeO<inf>3</inf> (KNN-LS-BF) ceramics were prepared by the combustion method using glycine as a fuel. The raw materials were mixed and calcined at various calcination temperatures (650-750°C) with different dwell time (0.5-3 h). Then, the calcined powders were pressed and sintered at various temperatures (1000-1100°C) with 0.5-4 h dwell time. The highest % perovskite orthorhombic phase was found in powder calcined at 700°C for 1 h. For the sintered pellets, the orthorhombic structure was found in ceramic sintered at 1075°C for 2 h using heating and cooling rate of 10°C/min. The SEM photographs showed square or rectangular morphology. The average grain size increased with the increasing of soak time. The highest densisty (4.47 g/cm3), maximum dielectric constant (ε<inf>r</inf> = 6180) and lowest dielectric loss (tanδ = 0.1) at T<inf>c</inf> were obtained in the sample sintered at 1075°C for 3 h. The densest sample showed the P <inf>r</inf> = 14.3 μC/cm3 and E<inf>c</inf> = 20.68 kV/cm at 40 kV/cm. © 2013 Copyright Taylor and Francis Group, LLC.
Some of the metrics are blocked by your
consent settings
Influence of sintering temperature on phase formation, microstructure and dielectric properties of calcium and strontium Doped BNT ceramics prepared via combustion technique
(2013-01-01)
Sittiketkorn, Panadda
;
Laowanidwatana, Artid
;
Vittayakorn, Naratip
;
Bongkarn, Theerachai
Influence of sintering temperature on phase formation, microstructure and dielectric properties of calcium and strontium doped BNT ceramics (BNTST20 and BNTCT2) were investigated. The BNTST20 and BNTCT2 ceramics were prepared using the combustion technique. The structural phase of the BNTST20 ceramics indexed in a cubic phase, while the BNTCT2 ceramics indexed in a rhombohedral phase. The average grain size tended to increase with increasing sintering temperature. The density and the dielectric constant at Curie temperatures increased with increasing sintering temperature up to 1200°C and 1150°C, thereafter they decreased for BNTST20 and BNTCT2 ceramics, respectively. Moreover, the highest density (5.59 and 5.57 g/cm3) ceramics exhibited the highest dielectric constant at Curie temperatures (∼4733 and ∼3218) for BNTST20 and BNTCT2, respectively. The ferroelectric properties were also investigated. © 2013 Copyright Taylor and Francis Group, LLC.
Some of the metrics are blocked by your
consent settings
The structural phase and microstructures of perovskite Ba(Ti 1-xZr x)O 3 ceramics using the combustion route
(2009-12-01)
Phungjitt, Nalinee
;
Panya, Perapong
;
Bongkarn, Theerachai
;
Vittayakorn, Naratip
Ba(Ti <inf>1-x</inf>Zr <inf>x</inf>)O <inf>3</inf>; BTZ (x = 0.20 and 0.25) ceramics are attractive candidates for dynamic random access memories, tunable microwave devices and capacitors. In this study, the preparation of BTZ powders and ceramics fabricated by the combustion method were studied in detail. The calcination and sintering conditions were performed from 600 to 900°C for 4 h and from 1300 to 1450°C for 2 h, respectively. The highest percentage of the cubic perovskite phase was found in the powders that were calcined at 800°C. A pure cubic perovskite structure was found in all ceramic samples. The average grain size increased with increasing sintering temperatures. Dielectric constant-temperature plots showed a maximum peak value of 7500 and 8300 for x = 0.20 and 0.25. The phase transition temperature of the BTZ ceramics occurred at 30°C and 10°C for x = 20 and 25, respectively. © 2009 World Scientific Publishing Company.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results