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RF 스퍼터링 시스템을 이용하여 증착한 비정질 Ga<sub>2</sub>O<sub>3</sub> 박막의 급속 열처리 조건에 따른 결정성과 광학적 특성 변화
김형민,박상빈,홍정수,김경환,Hyungmin Kim,Sangbin Park,Jeongsoo Hong,Kyunghwan Kim 한국전기전자재료학회 2023 전기전자재료학회논문지 Vol.36 No.6
The Ga<sub>2</sub>O<sub>3</sub> thin films were deposited using an RF sputtering system and the effect of crystallographic and optical properties under rapid thermal annealing conditions on Ga<sub>2</sub>O<sub>3</sub> thin film was evaluated. A rapid thermal annealing method can fabricate a crystalline Ga<sub>2</sub>O<sub>3</sub> thin film which is applied to various fields with a low cost and a high efficiency compared with the conventional post-annealing method. In this study, the Ga<sub>2</sub>O<sub>3</sub> treated at 900℃ for 1 min showed the beta and gamma phases in XRD measurement. In optical properties, the crystalline Ga<sub>2</sub>O<sub>3</sub> represented a high transmittance of more than 80% in the visible region and was calculated with a high optical bandgap energy of 4.58 eV. The beta and gamma phases Ga<sub>2</sub>O<sub>3</sub> can be obtained by adjusting the rapid thermal annealing temperatures, and the various properties such as the optical bandgap energy can be controlled. Moreover, it is expected that crystalline Ga<sub>2</sub>O<sub>3</sub> can be applied to various devices by controlling not only temperature but process time.
수열합성법을 이용한 Cu<sub>2</sub>O 입자의 합성
신성민 ( Seongmin Shin ),김경환 ( Kyunghwan Kim ),홍정수 ( Jeongsoo Hong ) 한국전기전자재료학회 2024 전기전자재료학회논문지 Vol.37 No.1
In this study, we successfully synthesized copper oxide (Cu<sub>2</sub>O) particles through a hydrothermal method at a relatively low temperature (150℃). The synthesis involved the precise control of molar concentrations of NaOH. Notably, Cu<sub>2</sub>O particles were effectively synthesized when NaOH concentrations of 0.15 M and 0.20 M were utilized. While attempts were made at different molar concentrations, the synthesis of pure Cu<sub>2</sub>O particles was only achieved at concentrations of 0.15 M and 0.20 M. In this experimental investigation, Cu<sub>2</sub>O synthesized under these specific conditions exhibited absorption characteristics within the wavelength range of 640 to 570 nm, consistently exhibiting a band gap energy of 1.9 eV. These Cu<sub>2</sub>O particles, characterized by their small band gap energy and straightforward synthetic method, hold significant promise for various applications including semiconductors and solar cells.
H₂O₂ 산화제를 이용한 δ-FeOOH의 합성과 입자 크기 제어
신성민 ( Seongmin Shin ),김경환 ( Kyunghwan Kim ),홍정수 ( Jeongsoo Hong ) 한국전기전자재료학회 2024 전기전자재료학회논문지 Vol.37 No.3
In this study, Iron (III) oxide-hydroxide (δ-FeOOH) was successfully synthesized using hydrogen peroxide (H₂O₂) as an oxidizing agent. The synthesis of δ-FeOOH was carried out by controlling the amount of H₂O₂, and pure δ-FeOOH was successfully synthesized in ranges from 0.2 mL to 0.6 mL of H₂O₂. The size of the synthesized δ-FeOOH particles was compared by controlling the amount of oxidant H₂O₂. The average particle size of the synthesized pure δ-FeOOH particles increased from 875.1 nm to 897.2 nm as the amount of H₂O₂ was increased. The optical properties of δ-FeOOH synthesized under these specific conditions were investigated. All δ-FeOOH showed a similar trend of increasing and decreasing light absorption from 800 nm to 400 nm, although there was a slight difference in the amount of light absorption, with the largest amount of light absorption at 410 nm. The band gap energy of δ-FeOOH through the Tauc plot method was about 2.1~2.2 eV when H₂O₂ was 0.2~1.4 mL. With a sufficient small particle size, simple control of that particle size, and a small band gap energy enough to absorb light in the visible spectrum, δ-FeOOH could be useful in a variety of applications, including photoelectrochemistry and battery electrodes.
산소 유입 없이 RF 스퍼터로 증착한 고품질 ITO 박막의 두께와 열처리 온도에 따른 박막의 특성 변화
성지하 ( Jiha Seong ),김형민 ( Hyungmin Kim ),신성민 ( Seongmin Shin ),김경환 ( Kyunghwan Kim ),홍정수 ( Jeongsoo Hong ) 한국전기전자재료학회 2024 전기전자재료학회논문지 Vol.37 No.3
In this study, ITO thin films were fabricated on a glass substrate at different thicknesses without introducing oxygen using RF sputtering system. The structural, electrical, and optical properties were evaluated at various thicknesses ranging from 50 to 300 mm. As the thickness of deposited ITO thin film become thicker from 50 to 100 mm, carrier concentration, mobility, and band gap energy also increased while the resistivity and transmittance decreased in the visible light region. When the film thickness increased from 100 to 300 mm, the carrier concentration, mobility, and band gap energy decreased while the resistivity and transmittance increased. The optimum electrical properties were obtained for the ITO film 100 nm. After optimizing the thickness, the ITO thin films were post-annealed at different temperatures ranging from 100 to 300℃. As the annealing temperature increased, the ITO crystal phase became clearer and the grain size also increased. In particular, the ITO thin film annealed at 300℃ indicated high carrier concentration (4.32 × 10<sup>21</sup> cm<sup>-3</sup>), mobility (9.01 cm2/V·s) and low resistivity (6.22 × 10<sup>-4</sup> Ω·cm). This means that the optimal post-annealing temperature is 300℃ and this ITO thin film is suitable for use in solar cells and display application.
FTS로 증착된 AZO 박막의 두께에 따른 구조적, 전기적, 광학적 특성 변화
김해찬 ( Haechan Kim ),김형민 ( Hyungmin Kim ),신성민 ( Seongmin Shin ),김경환 ( Kyunghwan Kim ),홍정수 ( Jeongsoo Hong ) 한국전기전자재료학회 2024 전기전자재료학회논문지 Vol.37 No.2
In this study, the structural, electrical, and optical properties of AZO films of various thicknesses are compared. The AZO films were deposited on a glass substrate by FTS (Facing-Target-Sputtering) This research was conducted to find the optimal thickness for Transparent Conductive Oxide (TCO). AZO has suitable properties for TCO such as low resistivity, and high transmittance. Thin films of all thicknesses showed a transmittance of over 80% in the visible light region and electrical properties improved as thickness increased. It was confirmed that the film of 300 nm thick had the best performance due to its low resistivity, and uniform surface. This research is expected to help find optimal conditions in various fields where TCO is used, such as solar cells, displays, and sensors in the future.