• Journal of the Korean Society for Precision Engineering
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• v.18 no.12
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• pp.167-176
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• 2001

The effects of heat treatments and testing temperatures on the mechanical properties of Invar materials were investigated through experiments, which call influence the formability in metal forming fields. Annealing temperatures were changed from $900^{\circ}C$ to $1200^{\circ}C$ with an increment of $100^{\circ}C$ under two different furnace atmosphere(vacuum and H$_2$gas). Microstructure and hardness tests were performed for annealed specimens at room temperature(RT) and tensile tests were also performed by changing annealing temperatures as well as testing temperatures from RT to $300^{\circ}C$. The grain size of annealed materials increased with increasing annealing temperature, while micro-hardness distributions showed almost same hardness values regardless of annealing temperatures. Strength ratio (tensile/yield strength), which influences the forming characteristics of sheet metal, remained almost constant for various experimental conditions in case of unannealed specimens. However, it showed increasing tendency with increasing both annealing and testing temperatures, particularly at the testing temperature higher than $200^{\circ}C$. Therefore it can be concluded that press formability of fully-annealed Invar material can be improved by warm forming technique.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.289.2-289.2
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• 2016

In-Ga-Zn-O(IGZO) receive great attention as a channel material for thin film transistors(TFTs) as next-generation display panel backplanes due to its superior electrical and physical properties such as a high mobility, low off-current, high sub-threshold slope, flexibility, and optical transparency. For the purpose of fabricating high performance IGZO TFTs, a thermal recovery process above a temperature of $300^{\circ}C$ is required for recovery or rearrangement of the ionic bonding structure. However diffused metal atoms from source/drain(S/D) electrodes increase the channel conductivity through the oxidation of diffused atoms and reduction of $In_2O_3$ during the thermal recovery process. Threshold voltage ($V_{TH}$) shift, one of the electrical instability, restricts actual applications of IGZO TFTs. Therefore, additional investigation of the electrical stability of IGZO TFTs is required. In this paper, we demonstrate the effect of Ti diffusion and modulation of interface traps by carrying out an annealing process on IGZO. In order to investigate the effect of diffused Ti atoms from the S/D electrode, we use secondary ion mass spectroscopy (SIMS), X-ray photoelectron spectroscopy, HSC chemistry simulation, and electrical measurements. By thermal annealing process, we demonstrate VTH shift as a function of the channel length and the gate stress. Furthermore, we enhance the electrical stability of the IGZO TFTs through a second thermal annealing process performed at temperature $50^{\circ}C$ lower than the first annealing step to diffuse Ti atoms in the lateral direction with minimal effects on the channel conductivity.

• Journal of the Korean Vacuum Society
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• v.10 no.3
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• pp.374-379
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• 2001

We have investigated the annealing effects on the optical properties of InAs quantum dots(QDs) capped with InGaAs(sample QDl), where InGaAs layer was deposited by opening Gallium, Arsenic, Indium and Arsenic shutters alternately with 3 periods, grown by molecular beam epitaxy. The emission wavelength of the sample of InAs QDs capped by GaAs barriers was observed to be blue-shifted as the annealing temperature was increased. On the other hand, the photoluminescence(PL) peak position of sample QD1 was observed to be red-shifted at the annealing temperature of up to $600^{\circ}C$ and, then, it was found to be blue-shifted at temperatures ranging from 700 to $800^{\circ}C$. The full width at half maximum values of sample QD1 subjected to annealing treatments show different behavior compared to typical InAs quantum dot structures.

• Journal of the Korean Vacuum Society
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• v.13 no.2
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• pp.72-78
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• 2004

Cu seed layers deposited by magnetron sputtering onto tantalum nitride barrier films were treated with ECR plasma and then the copper films were electroplated and rapid thermal annealed in an argon or nitrogen atmosphere at various temperatures ranging from 200 to $500^{\circ}C$. Changes in the microstructure and physical properties of the copper films electroplated on the hydrogen ECR plasma cleaned copper seed layers were investigated using X-ray diffraction (XRD), electron back-scattered diffraction (EBSD), and atomic force microscopy (AFM) analyses. It was found that the copper film undergoes complete recrystallization during annealing at a temperature higher than $400^{\circ}C$. The resistivity of the Cu film tends to decrease and the degree of (111) preferred orientation tends to increase as the annealing temperature increases. Theoptimum annealing condition for obtaining the film with the lowest resistivity, the smoothest surface and the highest degree of the (111) preferred orientation is rapid thermal annealing in a nitrogen atmosphere at $400^{\circ}C$ for 120 s. The resistivity and the surface roughness of the electroplated copper film annealed under this condition are 1.98 $\mu$O-cm and 17.77 nm, respectively.

• Journal of the Korean Vacuum Society
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• v.16 no.6
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• pp.433-438
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• 2007

We fabricated thin films of Au and Ta/Au with thicknesses of 30 nm and 5 nm/30nm, respectively on Si(100) or Si(111) substrates using a dc magnetron sputtering system. Grain sizes, roughness and conductivity for Au thin films are measured as a function of the annealing temperatures. We observed that the grain size of samples enlarged and the surface became rougher with increasing annealing temperature. The grain size and roughness were improved in the structure of Si/Ta/Au than Si/Au. Furthermore, the Si(100) substrate was more effective for decreasing the resistance for Ta/Au system than Si(111) substrate. We confirm that by inserting a Ta buffer layer in Si(100)/Au, surface roughness was reduced and by adjusting the annealing temperature the grain size were enlarged. Consequently, the Au thin-film has improved conductivity.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.367-373
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• 2006

We have observed a large increase in the magnetoresistance (MR) of Bi thin films, which were subjected to a post-annealing procedure at $268^{\circ}C$C, $3^{\circ}C$ below the Bi melting point. We have achieved an increase in the MR by 260-fold and 1200-fold at 5 K and 5 T after post-annealing, as compared with 190 and 620 for an as-deposited Bi film on PbTe/CdTe(111) and on mica, respectively. The large MR increase by post-annealing might be due to the improvement of crystallinity according to the x-ray analysis. However, post-annealing over a certain amount time showed the reduction in MR values.

• Journal of the Korean Vacuum Society
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• v.6 no.3
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• pp.206-212
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• 1997

The reflow characteristics of copper, which is expected to be used as interconnection materials in the next generation semiconductor devices, were investigated. Copper films were deposited on hole and trench patterns by metal organic chemical vapor deposition and annealed in nitrogen and oxygen ambient with the annealing temperatures ranging from $350^{\circ}C$ to $550^{\circ}C$. Copper films were not reflowed into the patterns upon the annealing in nitrogen ambient, but reflowed at the annealing temperature higher than $450^{\circ}C$ in oxygen ambient. It is considered that the reflow takes place as the heat generated by the oxidation of copper liquefies the copper film partly and the liquid copper fills the patterns for minimizing the surface energy and the potential energy. Upon the annealing in oxygen ambient, the copper oxide whose thickness was less than 300$\AA$ formed at the surface of an agglomerate and the resistivity of copper film increased drastically at an annealing temperature of $550^{\circ}C$ due to the copper agglomeration.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.304.2-304.2
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• 2014

Chalcogenides (Te,Se) and pnictogens(Bi,Sb) materials have been widely investigated as thermoelectric materials. Especially, Bi2Te3 (Bismuth telluride) compound thermoelectric materials in thin film and nanowires are known to have the highest thermoelectric figure of merit ZT at room temperature. Currently, the thermoelectric material research is mostly driven in two directions: (1) enhancing the Seebeck coefficient, electrical conductivity using quantum confinement effects and (2) decreasing thermal conductivity using phonon scattering effect. Herein we demonstrated influence of annealing temperature on structural and thermoelectrical properties of Bismuth-telluride-selenide ternary compound thin film. Te-rich Bismuth-telluride-selenide ternary compound thin film prepared co-deposited by thermal evaporation techniques. After annealing treatment, co-deposited thin film was transformed amorphous phase to Bi2Te3-Bi2Te2Se1 polycrystalline thin film. In the experiment, to investigate the structural and thermoelectric characteristics of Bi2Te3-i2Te2Se1 films, we measured Rutherford Backscattering spectrometry (RBS), X-ray diffraction (XRD), Raman spectroscopy, Scanning eletron microscopy (SEM), Transmission electron microscopy (TEM), Seebeck coefficient measurement and Hall measurement. After annealing treatment, electrical conductivity and Seebeck coefficient was increased by defect states dominated by selenium vacant sites. These charged selenium vacancies behave as electron donors, resulting in carrier concentration was increased. Moreover, Thermal conductivity was significantly decreased because phonon scattering was enhanced through the grain boundary in Bi2Te3-Bi2Te2Se1 polycrystalline compound. As a result, The enhancement of thermoelectric figure-of-merit could be obtained by optimal annealing treatment.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.203-203
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• 2014

Due to the electrical properties such as narrow bandgap and high carrier mobility, indium antimonide (InSb) has attracted a lot of attention recently. For the fabrication of electronic or photonic devices, an etching process is required. However, during etching process, enegetic ions can induce structural damages on the bombarded surface. Especially, InSb has a very weak binding energy between In atom and Sb stom, it can be easily damaged by impingement of ions. In the previous work, to evaluate the surface properties after Ar ion beam etching, the plasma-induced structural damage on the etched InSb(100) surface had been examined by resonant Raman spectroscopy. As a result, we demonstrated the relation between the enhanced transverse optical(TO) peak in the Raman spectrum and the ion-induced structral damage near the InSb surface. In this work, the annealing effect on the etched InSb(100) surface has investigated. Annealing process was performed at $450^{\circ}C$ for 10 minute under antimony ambient. As-etched InSb(100) surface had shown a strongly enhanced TO scattering intensity in the Raman spectrum. However, the annealing process with antimony flowing caused the intensity to recover due to the structural reordering and the reduction of antimony vacancies. It proves that the origin of enhanced TO scattering is Sb vacancies. Furthermore, it shows that etching-induced damage can be cured effectively by the following annealing process under Sb ambient.

• Journal of the Korean Vacuum Society
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• v.18 no.5
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• pp.377-383
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• 2009

Aluminum-doped zinc oxide (AZO) thin films were deposited on sapphire substrate by using radio-frequency magnetron sputtering and were performed in the temperature range of $600-900^{\circ}C$ by rapid thermal annealing (RTA). The crystallographic structure and the surface morphology were investigated by using X-ray diffraction and scanning electron microscopy, respectively. The crystallinity of the films was improved with increasing the annealing temperature and the average size of crystalline grains was found to be 50 nm. All the thin films showed an average transmittance of 92% in the wavelength range of 400-1100 nm. As the annealing temperature was increased, the bandgap energy was decreased and the violet photoluminescence (PL) signal at 400 nm replaced the ultraviolet PL signal. The electrical properties of the thin films showed a significant dependence on the annealing temperature.