Junggwon Yun - Academia.edu (original) (raw)

Papers by Junggwon Yun

Research paper thumbnail of Improved Electrical Characteristics of HgSe Nanoparticle-based Thin Film Transistors by Thermal Annealing

In this study, we fabricated the HgSe nanoparticle-based thin film transistors (TFTs) of back gat... more In this study, we fabricated the HgSe nanoparticle-based thin film transistors (TFTs) of back gate structure with PVA gate dielectric. The fabricated TFTs show the improved electrical characteristics in the mobility of /Vs and the on/off ratio of after annealing process at for 5 min. AFM images demonstrate that the decrease in surface roughness according to annealing process leads to the improvement of electrical characteristics. The change in drain current caused from the conditions of flexible substrate is investigated under 0.6% strain.

Research paper thumbnail of Thermoelectric characteristics of γ -Ag 2 Te nanoparticle thin films on flexible substrates

Thin Solid Films, 2017

In this study, we synthesized Ag 2 Te nanoparticles (NPs) in an aqueous solution and investigated... more In this study, we synthesized Ag 2 Te nanoparticles (NPs) in an aqueous solution and investigated the thermoelectric characteristics of Ag 2 Te NP thin films on bendable substrates. The Ag 2 Te NPs have an average size of 6 nm and a body-centered cubic γ-phase (or, γ-Ag 2 Te), and they exhibit typical p-type thermoelectric behaviors. The Seebeck coefficient and electrical conductivity of a γ-Ag 2 Te NP thin film are 1330 μV/K and 0.037 S/m, respectively, and the power factor is calculated to be 0.66 μW/mK 2. Furthermore, our bending study shows the stability of the thermoelectric characteristics of γ-Ag 2 Te NP thin films after the bending cycles.

Research paper thumbnail of N-channel thin-film transistors constructed on plastic by solution processes of HgSe nanocrystals

Microelectronic Engineering, 2009

We demonstrate bottom-gate thin-film transistors (TFTs) based on solution-processed HgSe nanocrys... more We demonstrate bottom-gate thin-film transistors (TFTs) based on solution-processed HgSe nanocrystals (NCs) on plastic substrates. Solid films made of spin-coated HgSe NCs were heated at a temperature of 150°C for 15 min to maximize the magnitude of their current, and these films were utilized as the channel layers of TFTs. A representative TFT with a bottom-gate Al 2 O 3 layer operated as a depletion-mode one with an n-channel, exhibiting a field effect mobility of 3.9 cm 2 /Vs and an on/off current ratio of about 10 2. In addition, the electrical characteristics of the TFT on bent substrates are briefly described.

Research paper thumbnail of Switching memory cells constructed on plastic substrates with silver selenide nanoparticles

Journal of Materials Science, 2011

Programmable metallization cell (PMC) memory is a kind of next generation non-volatile memory tha... more Programmable metallization cell (PMC) memory is a kind of next generation non-volatile memory that has attracted increasing attention in recent years as a possible replacement for flash memory. In spite of the considerable amount of research focused on the fabrication of non-volatile memories on plastic substrates with lightweight, thin, and bendable characteristics, there have been few studies on the fabrication of PCM memory on flexible substrates. In this study, we synthesized Ag 2 Se nanoparticles (NPs) by a positive-microemulsion method and constructed PMC memories on plastic substrates with programmable layers formed by the spin-coating of the Ag 2 Se NPs. To the best of the knowledge, this is the first attempt to construct PMC memory on plastic substrates by the spin-coating of Ag 2 Se NPs. The Ag 2 Se NPs synthesized in this study had a uniform size of 2 nm and interestingly showed a-phase (high temperature phase) stability at room temperature. Switching behaviors were observed through the voltage scanning on the fabricated memories with applicable switching voltages. However, the resistance ratios of the off-state to the on-state were quite small. The possible reasons for the a-phase stability of the Ag 2 Se NPs at room temperature and the detailed memory characteristics will be described in this article.

Research paper thumbnail of Resistance switching memory devices constructed on plastic with solution-processed titanium oxide

Journal of Materials Chemistry, 2009

ABSTRACT

Research paper thumbnail of Optical Heating of Ink-Jet Printable Ag and Ag–Cu Nanoparticles

Japanese Journal of Applied Physics, 2008

Ink-jet printable Ag nanoparticles (NPs) and Ag-Cu alloy NPs were synthesized by the polyol metho... more Ink-jet printable Ag nanoparticles (NPs) and Ag-Cu alloy NPs were synthesized by the polyol method, and interconnection lines composed of these NPs were fabricated on poly(ether sulfone) substrates. The effect of optical heating on the resistivity of the interconnections was investigated as functions of the irradiation time and power of the 488-nm wavelength light. The resistivities of the interconnection lines composed of the NPs were decreased by 7-10 times after the irradiation of the light with a power of 400 mW for 30 min, compared with the interconnection lines composed of the as-synthesized NPs. In addition, the change in the current of the interconnection line when the substrate is bent is discussed in this paper.

Research paper thumbnail of Flexible logic circuits composed of chalcogenide-nanocrystal-based thin film transistors

Nanotechnology, 2010

Complementary NAND and NOR gates composed of p-channel HgTe-nanocrystal (NC) films and n-channel ... more Complementary NAND and NOR gates composed of p-channel HgTe-nanocrystal (NC) films and n-channel HgSe-NC films were constructed on back-gate patterned plastic substrates. The NAND gate was made of two HgTe-p-channel thin film transistors (TFTs) in parallel and two HgSe-n-channel TFTs in series. The NOR gate was built up with both two HgSe-n-channel TFTs in parallel and two HgTe-p-channel TFTs in series. The mobility and on/off ratio for the p-channel TFTs were estimated to be 0.9 cm(2) V(-1) s(-1) and 10, respectively, and those for the n-channel TFTs were measured to be 1.8 cm(2) V(-1) s(-1) and 10(2), respectively. The NAND and NOR gates were operated with gains of 1.45 and 1.63 and transition widths of 7.8 and 6.2 V, respectively, at room temperature in air. In addition, the operations of the NAND and NOR logics are reproducible for up to 1000 strain cycles.

Research paper thumbnail of Improved Electrical Characteristics of HgSe Nanoparticle-based Thin Film Transistors by Thermal Annealing

In this study, we fabricated the HgSe nanoparticle-based thin film transistors (TFTs) of back gat... more In this study, we fabricated the HgSe nanoparticle-based thin film transistors (TFTs) of back gate structure with PVA gate dielectric. The fabricated TFTs show the improved electrical characteristics in the mobility of /Vs and the on/off ratio of after annealing process at for 5 min. AFM images demonstrate that the decrease in surface roughness according to annealing process leads to the improvement of electrical characteristics. The change in drain current caused from the conditions of flexible substrate is investigated under 0.6% strain.

Research paper thumbnail of Thermoelectric characteristics of γ -Ag 2 Te nanoparticle thin films on flexible substrates

Thin Solid Films, 2017

In this study, we synthesized Ag 2 Te nanoparticles (NPs) in an aqueous solution and investigated... more In this study, we synthesized Ag 2 Te nanoparticles (NPs) in an aqueous solution and investigated the thermoelectric characteristics of Ag 2 Te NP thin films on bendable substrates. The Ag 2 Te NPs have an average size of 6 nm and a body-centered cubic γ-phase (or, γ-Ag 2 Te), and they exhibit typical p-type thermoelectric behaviors. The Seebeck coefficient and electrical conductivity of a γ-Ag 2 Te NP thin film are 1330 μV/K and 0.037 S/m, respectively, and the power factor is calculated to be 0.66 μW/mK 2. Furthermore, our bending study shows the stability of the thermoelectric characteristics of γ-Ag 2 Te NP thin films after the bending cycles.

Research paper thumbnail of N-channel thin-film transistors constructed on plastic by solution processes of HgSe nanocrystals

Microelectronic Engineering, 2009

We demonstrate bottom-gate thin-film transistors (TFTs) based on solution-processed HgSe nanocrys... more We demonstrate bottom-gate thin-film transistors (TFTs) based on solution-processed HgSe nanocrystals (NCs) on plastic substrates. Solid films made of spin-coated HgSe NCs were heated at a temperature of 150°C for 15 min to maximize the magnitude of their current, and these films were utilized as the channel layers of TFTs. A representative TFT with a bottom-gate Al 2 O 3 layer operated as a depletion-mode one with an n-channel, exhibiting a field effect mobility of 3.9 cm 2 /Vs and an on/off current ratio of about 10 2. In addition, the electrical characteristics of the TFT on bent substrates are briefly described.

Research paper thumbnail of Switching memory cells constructed on plastic substrates with silver selenide nanoparticles

Journal of Materials Science, 2011

Programmable metallization cell (PMC) memory is a kind of next generation non-volatile memory tha... more Programmable metallization cell (PMC) memory is a kind of next generation non-volatile memory that has attracted increasing attention in recent years as a possible replacement for flash memory. In spite of the considerable amount of research focused on the fabrication of non-volatile memories on plastic substrates with lightweight, thin, and bendable characteristics, there have been few studies on the fabrication of PCM memory on flexible substrates. In this study, we synthesized Ag 2 Se nanoparticles (NPs) by a positive-microemulsion method and constructed PMC memories on plastic substrates with programmable layers formed by the spin-coating of the Ag 2 Se NPs. To the best of the knowledge, this is the first attempt to construct PMC memory on plastic substrates by the spin-coating of Ag 2 Se NPs. The Ag 2 Se NPs synthesized in this study had a uniform size of 2 nm and interestingly showed a-phase (high temperature phase) stability at room temperature. Switching behaviors were observed through the voltage scanning on the fabricated memories with applicable switching voltages. However, the resistance ratios of the off-state to the on-state were quite small. The possible reasons for the a-phase stability of the Ag 2 Se NPs at room temperature and the detailed memory characteristics will be described in this article.

Research paper thumbnail of Resistance switching memory devices constructed on plastic with solution-processed titanium oxide

Journal of Materials Chemistry, 2009

ABSTRACT

Research paper thumbnail of Optical Heating of Ink-Jet Printable Ag and Ag–Cu Nanoparticles

Japanese Journal of Applied Physics, 2008

Ink-jet printable Ag nanoparticles (NPs) and Ag-Cu alloy NPs were synthesized by the polyol metho... more Ink-jet printable Ag nanoparticles (NPs) and Ag-Cu alloy NPs were synthesized by the polyol method, and interconnection lines composed of these NPs were fabricated on poly(ether sulfone) substrates. The effect of optical heating on the resistivity of the interconnections was investigated as functions of the irradiation time and power of the 488-nm wavelength light. The resistivities of the interconnection lines composed of the NPs were decreased by 7-10 times after the irradiation of the light with a power of 400 mW for 30 min, compared with the interconnection lines composed of the as-synthesized NPs. In addition, the change in the current of the interconnection line when the substrate is bent is discussed in this paper.

Research paper thumbnail of Flexible logic circuits composed of chalcogenide-nanocrystal-based thin film transistors

Nanotechnology, 2010

Complementary NAND and NOR gates composed of p-channel HgTe-nanocrystal (NC) films and n-channel ... more Complementary NAND and NOR gates composed of p-channel HgTe-nanocrystal (NC) films and n-channel HgSe-NC films were constructed on back-gate patterned plastic substrates. The NAND gate was made of two HgTe-p-channel thin film transistors (TFTs) in parallel and two HgSe-n-channel TFTs in series. The NOR gate was built up with both two HgSe-n-channel TFTs in parallel and two HgTe-p-channel TFTs in series. The mobility and on/off ratio for the p-channel TFTs were estimated to be 0.9 cm(2) V(-1) s(-1) and 10, respectively, and those for the n-channel TFTs were measured to be 1.8 cm(2) V(-1) s(-1) and 10(2), respectively. The NAND and NOR gates were operated with gains of 1.45 and 1.63 and transition widths of 7.8 and 6.2 V, respectively, at room temperature in air. In addition, the operations of the NAND and NOR logics are reproducible for up to 1000 strain cycles.