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윤종환 한국물리학회 2017 새물리 Vol.67 No.6
본 연구에서는 니켈 막을 촉매로 비정질 실리콘 박막을 사용하여 실리카 나노와이어를 형성하고, 실리콘 웨이퍼를 사용하여 형성된 실리카 나노와이어와 구조적, 물리적 특성을 비교 분석하였다. 비정질 실리콘 박막은 플라즈마 화학 기상 증착 방법으로 제조하였으며, 표면에 니켈 막을 진공 증착한 후 약 1100 $^{\circ}$C 온도에서 1시간 동안 열처리 하여 나노와이어를 형성하였다. 주사현미경, 투과현미경 및 포토루미네슨스 측정을 통해 나노와이어의 미세구조 및 물성을 조사하였으며, 나노와이어 형성 메커니즘, 미세 구조 및 발광 특성 등에서 실리콘 웨이퍼의 나노와이어와 거의 차이점이 없다는 사실을 확인하였다. 연구 결과로부터 실리카 나노와이어는 기상-액상-고상 (vapor-liquid-solid) 과정보다는 고상-액상-고상 (solid-liquid-solid) 메커니즘에 의해 형성되는 것으로 이해된다. Silica nanowires were fabricated by using amorphous silicon (a-Si) films with Ni as a catalyst, and their morphological and physical properties were compared with those of a crystalline silicon (c-Si) wafer. The fabrication was achieved by thermal annealing of a-Si films, which were prepared by using plasma-enhanced chemical vapor deposition, coated with Ni films at 1100 $^{\circ}$C. No distinct differences in the formation mechanism, the morphology and the emission characteristics between a-Si and c-Si, as deduced from scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence measurements, were found the results show that the growth of silica nanowires is mediated by a solid-liquid-solid mechanism rather than by the vapor-liquid-solid process.
Effects of Hydrogen Treatments of Silicon Substrates on Pore Formation
윤종환,장유성 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
The effects of prehydrogenation of Si substrates on porous silicon formation have been investigated. Porous silicon layers were prepared by electrochemically anodizing Si substrates exposed to an atomic hydrogen plasma. Hydrogen exposure is shown to significantly suppress pore formation and to result in an increase in the photoluminescence (PL) intensity. A 90-min H exposure at 100 ℃ is shown to result in a reduction in pore density by a factor of 0.02 and a two-fold increase in PL intensity. These results arise from hydrogenation of the Si substrate by hydrogen exposure and support a suggestion that pore formation can be hindered by the existence of Si-H bonds. The effects of prehydrogenation of Si substrates on porous silicon formation have been investigated. Porous silicon layers were prepared by electrochemically anodizing Si substrates exposed to an atomic hydrogen plasma. Hydrogen exposure is shown to significantly suppress pore formation and to result in an increase in the photoluminescence (PL) intensity. A 90-min H exposure at 100 ℃ is shown to result in a reduction in pore density by a factor of 0.02 and a two-fold increase in PL intensity. These results arise from hydrogenation of the Si substrate by hydrogen exposure and support a suggestion that pore formation can be hindered by the existence of Si-H bonds.
Hydrogen Passivation of Luminescence-Quenching Defects in Si Nanocrystals
윤종환,정윤진 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
Si nanocrystals embedded in silicon-dioxide films are exposed to either atomic or molecular hydrogen at 300 ℃. Both exposures are shown to result in an increase in the photoluminescence (PL) intensity with increasing exposure time, followed by saturation. The saturation intensity strongly depends on the hydrogen type, showing a larger PL intensity for atomic hydrogen than for molecular hydrogen. Furthermore, the thermal stability of the PL intensity induced by atomic hydrogen exposure is shown to be less than that induced by molecular hydrogen exposure. These results demonstrate the presence of at least two different luminescence-quenching defects at the Si nanocrystal/SiO2 interface: one that is passivated by atomic hydrogen and one that is only passivated by molecular hydrogen.
Fabrication of ZnO Nanosheets by Chemical Annealing of Pre-Synthesized Zn Sheets
윤종환 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.74 No.2
In this work, zinc oxide (ZnO) nanosheets were fabricated by chemically annealing pre-synthesized Zn sheets by exposing them to an oxygen plasma at low temperatures. The resulting ZnO nanosheets were found to have a wurtzite hexagonal structure similar to that of the pre-synthesized Zn sheets. Moreover, they exhibited growth characteristics along the [101] preferred direction, a Raman peak located around 590 cm1, and photoluminescence spectra with peaks at approximately 380 nm and 500 nm. The results show that ZnO nanosheets can be obtained by oxidizing Zn sheets via a self-catalyzed vapor-solid mechanism.