Ruttanapun, Chesta

Preferred name

Ruttanapun, Chesta

Alternative Name

Ruttanapun, C.

Main Affiliation

School of Science

chesta.ru@kmitl.ac.th

Now showing 1 - 10 of 89

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Investigating the High Electron Mobilities and Transport Scattering Processes in 2D Non-Van Der Waals Bi2O2Te Nanosheet Films
(2025-11-01)
Chomngam, Sasithorn
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Pimanpang, Samuk
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Ruttanapun, Chesta
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Rujisamphan, Nopporn
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Thongnum, Anusit
Bismuth oxytelluride (Bi<inf>2</inf>O<inf>2</inf>Te) nanosheets, a 2D non-van der Waals (2D-nvdW) semiconductor, has exceptionally high carrier mobilities, between 496 and 584 cm2V−1s−1 at room temperature (RT). Its numerous potential applications in multifunctional electronic devices have sparked much research interest. However, comprehensive explanations of the high RT mobilities and transport scattering processes in the Bi<inf>2</inf>O<inf>2</inf>Te nanosheet films are still sought. Herein, measured mobility data, between 5000 and 54,074 cm2V−1s−1 at 2 K and 125–584 cm2V−1s−1 at 300 K, are examined and modeled considering several scattering sources, including ionized impurities, longitudinal optical (LO) phonon, and electron–electron interactions. The total mobility based on three scattering mechanisms provided good quantitative agreement with the experimental results from thicknesses ranging from 21.0 to 55.0 nm. Ionized impurity scattering limits mobility at temperatures lower than 50 K, but LO phonon and electron–electron scatterings dominate at temperatures between 50 and 300 K. When the thickness decreases to 21.0 nm, electron-electron scattering strength becomes stronger and the RT mobility drops to 125 cm2 V−1s−1. These findings advance the knowledge of the charge transport mechanisms that underlie the Bi<inf>2</inf>O<inf>2</inf>Te nanosheet and provide more details for other 2D-nvdW and 2D semiconductors.
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Enhancing thermoelectric properties of nanostructure Ga-doped ZnO prepared by microwave-hydrothermal synthesizing with comparing to calculation results
(2019-01-01)
Jantrasee, Sakwiboon
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Moontragoon, Pirot
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Pinitsoontorn, Supree
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Ruttanapun, Chesta
In this work, Zn<inf>1-x</inf>Ga<inf>x</inf>O, (x=0, 0.01, 0.02 and 0.03) powders were prepared using the hydrothermal method with accelerated-microwave heating system. The nanostructure Zn<inf>1-x</inf>Ga<inf>x</inf>O were successfully fabricated via microwave heating method with presenting of the anisotropic hexagonal prism shape in perpendicular to c-axis and self-aggregated nano-particle. The Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) technique reveled the nanostructure particle size sample of the ZnO and the Ga-doped ZnO as in the range of 80-100 nmand 50-100 nm, respectively. The computer simulation showed the thermoelectric properties of ZnO enhancing by doping Gallium ZnO. The experimental results of thermoelectric properties for nanostructures Ga-doped ZnO nanomaterials was enhanced electrical conductivity and reduced thermal conductivity. The Seebeek value of the Ga-doped ZnO nanomaterials was difference from the ZnO-based. All ZT value of the Gadoped ZnO nanomaterials were higher than that the ZnO-based. The highest ZT value of 0.08 was obtained from2%Ga-doped ZnO at 773 K. The nanostructure of the Zn<inf>1-x</inf>Ga<inf>x</inf>Onanomaterials were completely prepared by the hydrothermal-microwave heating with enhancing thermoelectric properties. The Ga-doped ZnO nanomaterials are potential materials for moderate temperature thermoelectric applications.
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Topology of boron substitutional defects in single-walled carbon nanotubes: A first-principles study
(2024-06-01)
Prachamon, Wutthisak
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Jaiboon, Oruethai
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Komin, Sittipong
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Ruttanapun, Chesta
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Limpijumnong, Sukit
This is a theoretical study of boron-doped single-walled carbon nanotubes. The same topology of primitive nanodomains, located at different positions on single-walled carbon nanotubes, leads to different electronic band structures. We propose a ϕ term. Density functional theory was corrected for van der Waals interactions and used to carry out the periodic boundary condition geometry optimization, where boron formed the topologies of primitive nanodomains. The calculated bulk structure and local structure spectroscopic parameters can be used for comparison with experimental results to confirm the theoretical models.
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The direct measurement of the photorefractive grating on anisotropic self diffraction using digital holography
(2014-09-02)
Plaipichit, Suwan
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Buranasiri, Prathan
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Ruttanapun, Chesta
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Jindajitawat, Phumin
In this paper, the measurement of grating period in photorefractive anisotropic self diffraction by using digital holography technique is proposed. In our experimental setup, He -Ne laser beam with wavelength of 632.8 nm has been separated and then incident on photorefractive cerium doped barium titanate crystal to produce photorefractive index grating. The transmitted probe beam, which contains phase and amplitude has been expanded and recorded on digital camera. To explore the grating periods, both phase and amplitude of the images are reconstructed by numerical process using computer. Then the grating periods in photorefractive anisotropic self diffraction have been measured. The results show grating periods, holograms and their reconstruction. © 2014 Taylor & Francis Group, LLC.
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Preparation, characterization and finite element computation of Cu(Al 1/2Fe1/2)O2 Delafossite-oxide themoelectric generator module
(2014-09-02)
Ruttanapun, Chesta
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Jindajitawat, Phumin
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Buranasiri, Prathan
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Naenkieng, Daengdesh
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Boonyopakorn, Narongchai
The CuAl<inf>1/2</inf>Fe<inf>1/2</inf>O<inf>2</inf> delafossite oxide has been synthesized by solid state reaction method for studying thermoelectric properties and measuring thermoelectric generator output electric power. The Finite Element technique was used to compute the output voltage of thermoelectric generator in applying temperature difference on a single bar and a module model with compared to the measurement results. The measurement results of positive sign Seebeck coefficient confirm the p-type conductor of the sample. The properties of Seebeck coefficient, electrical conductivity, and thermal conductivity are range from 260 to 310V/K, from 7 to16 S/cm and from 2.5 to 3.5 W/cm-K,respectively, in the temperature range of 300 to 960 K. The output voltage of the single bar in dimension 4.2 × 2.5 × 20 mm 3 obtained 0.5 to 3 mV on applying temperature difference from 1 to 10 K closely to the Finite Element result. The computing results of the thermoelectric single bar and module in high temperature reveal the output electric voltage of CuAl<inf>1/2</inf>Fe<inf>1/2</inf>O<inf>2</inf> oxide raises with the temperature and the number of thermoelectric leg increase. In important results, the high value of electric voltage is obtained 0.2 and 0.4 V for the single bar and the module at 950 K. © 2014 Taylor & Francis Group, LLC.
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Development of high-temperature multi-magnetron microwave furnace for material processing
(2019-05-01)
Boonthum, Direk
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Chanprateep, Singkarn
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Ruttanapun, Chesta
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Nisoa, Mudtorlep
In this paper, we have successfully developed a multi-magnetron multi-mode high-temperature furnace for material processing. The SiC crucible could be heated to 1000 oC within only a few minutes. Synthesis of thermoelectric Al-doped ZnO in a microwave furnace took less than 20 times the time of a conventional furnace, and the electric power of Al-doped ZnO was higher. The furnace was fabricated according to the computational optimization using Comsol. Two waveguides were mounted on opposite sides of the cavity must have 90 degree relative angle. For impedance matching and power combination, the multi-mode rectangular cavity must have dimensions of 28 x 28 x 28 cm3. Therefore, electric fields were maximized at the center of the cavity and minimized in the waveguides. To suppress the microwave leakage within safety standards, choke parameters were obtained. The calculations and measurements reinforce that scaling up can be done in the future.
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Impact of Sn4+ Substitution at Cr3+ Sites on Thermoelectric and Electronic Properties of p-Type Delafossite CuCrO2
(2020-01-01)
Jantrasee, Sakwiboon
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Ruttanapun, Chesta
The effects of Sn4+ substitution at Cr3+ sites on the thermoelectric and electronic properties of p-type delafossite CuCrO<inf>2</inf> have been studied. CuCr<inf>1−x</inf>Sn<inf>x</inf>O<inf>2</inf> (x = 0.01, 0.03) samples were prepared via conventional solid-state reaction. The Seebeck coefficient results confirmed that all the samples exhibited p-type conduction. X-ray photoelectron spectroscopy verified the presence of Sn4+ ions and the appearance of mixed-state Cr3+/Cr2+ ions. The experimental results revealed that addition of Sn impacted the electrical conductivity due to the mixed Cu1+/Cu2+ states while the Seebeck coefficient was affected by the mixed Cr3+/Sn4+ states. The electrical conductivity was governed by the polaron hopping mechanism, and the large Seebeck coefficient was controlled by the spin and orbital degeneracy of the mixed Cr3+/Sn4+ ions. The electrical conductivity activation energy values were 0.410 eV and 0.407 eV while the thermal activation energy values were 0.208 eV and 0.160 eV, for x = 0.01 and 0.03, respectively. The results confirm that Sn4+ substitution at Cr3+ sites impacted the Seebeck coefficient and electronic behavior of delafossite CuCrO<inf>2</inf> oxide even for low dopant levels of x = 0.01 and 0.03, resulting in p-type conduction and optically conducting materials.
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Optical parametric amplification in one-dimensional photonic bandgap structures
(2013-09-01)
Wicharn, Surawut
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Buranasiri, Prathan
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Ruttanapun, Chesta
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Jindajitawat, Phumin
In this paper, optical parametric amplification based on the degenerate four-wave mixing principle in a one-dimensional photonic bandgap (PBG) structure has been numerically studied. First, the multiple scale method was introduced to derive a complete set of nonlinear coupled-mode equations for a finite structure with different inhomogeneous nonlinear coefficients than those used in previous works. This finite structure is composed of 680 dielectric layers, which are alternating half-wave/eight-wave films. The wavelengths of the pump, signal, and idler pulses have been determined from the transmission spectrum, which was illustrated by using the transfer matrix method. The parametric interaction of the pump, signal, and idler pulses inside PBG structure has been numerically simulated by using the splitstep Fourier transform method. The results of the simulation have shown that the intensities of the signal and idler have exponential growth with respect to the number of layers in the medium. Meanwhile, pump wavevector detuning directly affects the intensities of both pulses due to a band-edge phase-matching condition that might be achieved from only one optimal detuning parameter. Moreover, both the amplification gain and the conversion efficiency of the idler pulse have been shown to be dependent on the bandwidth of the pump pulse spectrum. A very narrow pulse, with a bandwidth much less than the relevant transmission peak, enables the highest amplification and conversion efficiency in this medium because the most efficient phase-matched condition occurs in this situation. Finally, the conversion efficiency grows exponentially with input pump intensity for several input signal intensities. Furthermore, the maximum conversion efficiencies directly vary with input signal intensity. © 2013 Optical Society of America.
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Effects of spin entropy and lattice strain from mixed-trivalent Fe3+/Cr3+ on the electronic, thermoelectric and optical properties of delafossite CuFe1-xCrxO2 (x = 0.25, 0.5, 0.75)
(2015-11-18)
Ruttanapun, Chesta
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Maensiri, Santi
Mixed-trivalent Fe3+/Cr3+ content CuFe<inf>1-x</inf>Cr<inf>x</inf>O<inf>2</inf> (x = 0.25, 0.5, and 0.75) compounds were synthesized to investigate the effects of spin entropy, and lattice strain on their electronic, thermoelectric and optical properties. The XPS results showed the existence of mixed Cu1+/Cu2+, Fe3+/Fe4+ and Cr2+/Cr3+ ion states in the structures. The mixed Fe3+/Cr3+ions caused a strong correlation to occur between the spin and the orbitals of the carriers in the octahedral layer of the sample, affecting the carrier degeneracy Seebeck coefficient behaviour, and the Cu2+ and Fe4+ ions caused an effect of enhancing the electric conductivity. These effects meant that CuFe<inf>0.75</inf>Cr<inf>0.25</inf>O<inf>2</inf> had the highest electrical conductivity, an enhanced Seebeck coefficient compared to that of CuFeO<inf>2</inf>-based compounds, and the highest thermopower value. The lowest thermal conductivity was that of CuFe<inf>0.5</inf>Cr<inf>0.5</inf>O<inf>2</inf>, which was a result of the mismatched atomic radii of the mixed trivalent Fe3+(0.645 Å)/Cr3+(0.615 Å), which caused the lattice strain to occur in the structure and thus affected the point defect scattering of the phonon thermal conductivity. The lowest total thermal conductivity was that of CuFe<inf>0.5</inf>Cr<inf>0.5</inf>O<inf>2</inf>, because it had the maximum lattice strain. Overall, the effect of the mixed trivalent elements caused CuFe<inf>0.75</inf>Cr<inf>0.25</inf>O<inf>2</inf> to have the highest value of the dimensionless figure of merit ZT, with a value that was four times that of CuFeO<inf>2</inf>-based compounds and six times that of CuCrO<inf>2</inf>-based compounds. With regard to optical properties, the lattice strain causes the indirect optical gap to increase with increasing x content, but has no effect on the direct optical gap. These results verified that the mixed-trivalent Fe3+/Cr3+ content of CuFe<inf>1-x</inf>Cr<inf>x</inf>O<inf>2</inf> (x = 0.25, 0.5, and 0.75) affected the electronic, thermoelectric and optical properties of the structure by causing spin entropy and lattice strain to occur.
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Electrical and optical properties of p-type CuFe1-xSn xO2 (x = 0.03, 0.05) delafossite-oxide
(2013-01-14)
Ruttanapun, Chesta
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Boonchom, Banjong
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Thongkam, Montree
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Kongtaweelert, Samart
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Thanachayanont, Chanchana
The CuFe<inf>1-x</inf>Sn<inf>x</inf>O<inf>2</inf> (x = 0.03, 0.05) delafossite samples have been synthesized by a solid-state reaction to investigate electrical and optical properties of the transparent conducting oxide materials. Crystal structure was characterized by XRD. The electrical conductivity and Seebeck coefficient were measured in the high temperature range of 300 to 960 K, while the Hall coefficient, XPS, and UV-VIS-NIR spectra were analyzed at room temperature. The XRD peaks of the samples indicate the delafossite structure phase, and the XPS spectra reveal the stable Sn 2+-doping state. The Seebeck and Hall coefficient display a positive sign indicating the p-type conducting oxide. The optical allowed direct gap is 3.45 eV as a visible-transparent material. The activation energies for polaron hopping between Sn2+ sites and Fe3+ sites of 36 and 32 meV are obtained from the samples having x = 0.03 and 0.05, respectively. The CuFe<inf>1-x</inf>Sn<inf>x</inf>O<inf>2</inf> delafossite oxide compounds, of which the Fe3+ sites in the CuFeO<inf>2</inf> are substituted by the Sn2+ ions, are p-type transparent conducting oxide materials. The activation energy is found to decrease with an increased in Sn content. © 2013 American Institute of Physics.

Ruttanapun, Chesta

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