http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Mesfin Abayneh Kebede (검색결과 6 건)
- 무료
- 기관 내 무료
- 유료
-
Effect of Temperature on GaN Nanowires Fabricated via Thermal Heating of GaN Powders
김현우,Mesfin Abayneh Kebede,김효성,나한길,양주찬,이종무 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.1
GaN nanowires have been successfully synthesized by heating GaN powders under flowing ammonia gas in a temperature range of 950-1050 °C. The nanowire morphology was changed with varying temperature, and higher temperature favored thinner nanowires. The growth mechanisms of GaN nanowires at 950 °C included a vapor-liquid-solid process. The photoluminescence (PL) spectra of the samples commonly exhibited violet to yellow emission, whereas red emission occurred preferentially in samples synthesized at lower temperature. We have discussed the possible mechanisms by which growth temperature affected the nanowire morphology and PL spectrum.
-
Characteristics of SiOx-Cored Composite Nanowires with Pd Shell Layers
김현우,Mesfin Abayneh Kebede,김효성 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.4
This paper describes the fabrication of Pd-coated SiOx nanowires via a simple approach and reports the effects of subsequent thermal annealing. While the as-synthesized Pd-coated SiOx nanowires exhibited smooth onedimensional (1D) nanostructures, the thermal annealing induced a rough surface. X-ray diffraction, selected area electron diffraction, and lattice-resolved transmission electron microscopy coincidentally revealed that the assynthesized Pd-coated SiOx nanowires were comprised of a cubic Pd phase, whereas annealing generated a tetragonal PdO phase. Micro-Raman spectroscopy measurements showed the presence of 630 cm_1-peak, which can be assigned to the B1g mode of single crystal PdO, whether samples had been annealed or not. Although both Pd and PdO phases did not exhibit PL emission, the PL intensity of core SiOx nanowires has been significantly reduced by the Pd-coating, presumably due to the covering effect. PACS: 81.07.-b; 81.05.Bx; 78.55.-m; 78.30.-J; 61.05.cp; 68.37.Hk; 68.37.Lp This paper describes the fabrication of Pd-coated SiOx nanowires via a simple approach and reports the effects of subsequent thermal annealing. While the as-synthesized Pd-coated SiOx nanowires exhibited smooth onedimensional (1D) nanostructures, the thermal annealing induced a rough surface. X-ray diffraction, selected area electron diffraction, and lattice-resolved transmission electron microscopy coincidentally revealed that the assynthesized Pd-coated SiOx nanowires were comprised of a cubic Pd phase, whereas annealing generated a tetragonal PdO phase. Micro-Raman spectroscopy measurements showed the presence of 630 cm_1-peak, which can be assigned to the B1g mode of single crystal PdO, whether samples had been annealed or not. Although both Pd and PdO phases did not exhibit PL emission, the PL intensity of core SiOx nanowires has been significantly reduced by the Pd-coating, presumably due to the covering effect. PACS: 81.07.-b; 81.05.Bx; 78.55.-m; 78.30.-J; 61.05.cp; 68.37.Hk; 68.37.Lp
-
김현우,Mesfin Abayneh Kebede,Hyo Sung Kim 한국물리학회 2010 Current Applied Physics Vol.10 No.1
Al-doped ZnO (AZO) shell layers were coated on core ZnO nanowires to fabricate ZnO/AZO core–shell nanowires. The energy-dispersive X-ray spectra confirmed the presence of Al element in the shell layers,and the lattice resolved transmission electron microscopy image revealed that these layers corresponded to the hexagonal ZnO structure. The X-ray diffraction pattern exhibited a shift of the ZnO peaks, suggesting the substitutive incorporation of Al into the ZnO lattice. The A1(LO) mode line in the Raman spectra was enhanced by the AZO coating. In the photoluminescence measurements, the AZO coating enhanced the intensity ratio of the UV to green emission.
-
MgO-Core/ZnO-shell Nanocables Sheathed by Using the Sputtering Technique
김효성,김현우,이총무,Mesfin Abayneh Kebede,유건호,Doo Young Kim 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.5
We demonstrated the successful fabrication of MgO-core/ZnO-shell nanowires, in which the shell layers were deposited by using the sputtering technique. Transmission electron microscopy investigations revealed that core nanowires were surrounded by a ZnO shell layer. At 298 K, the photoluminescence (PL) peak intensity ratio (green/UV) decreased with increasing ZnO shell thickness. In regard to the effect of temperature, the intensity of the green emission band was progressively decreased with increasing measurement temperature. We discuss the possible associated PL emission mechanisms.
-
Catalyst-free synthesis of GeO2 nanowires using the thermal heating of Ge powders
Hyoun Woo Kim,Jong Woo Lee,Mesfin Abayneh Kebede,김현우,이종무 한국물리학회 2009 Current Applied Physics Vol.9 No.6
Germanium dioxide (GeO2) nanowires have been synthesized by means of the simple evaporation of solid Ge powders, without using metal catalysts. The nanowires, with a diameter of about 90–200 nm, were characterized using scanning electron microscopy (SEM), X-ray diffractometry (XRD), and transmission electron microscopy (TEM). The obtained GeO2 nanowires were crystalline with a hexagonal structure. The growth mechanism was discussed with respect to the vapor–solid process. The photoluminescence measurement revealed two emission peaks at about 2.45 eV and 2.91 eV at room temperature, opening up a route to potential applications in future optoelectronic nanodevices. Raman measurement of as-synthesized GeO2 nanowires was made at room temperature.
-
Fabrication and annealing effects of SnO2/SiOx nanocables sheathed by the sputtering technique
김현우,Seung Hyun Shim,Jong Woo Lee,Hyo Sung Kim,Mesfin Abayneh Kebede,나한길,양주찬,공명호,이종무 한국물리학회 2010 Current Applied Physics Vol.10 No.1
We reported an approach, in which we have produced the nano-sized crystalline tin oxide (SnO2) particles with rutile structure. SnO2 nanowires were coated with a shell layer of SiOx via a sputtering method. Transmission electron microscopy and elemental mapping investigations revealed that the nanostructures consisted of a crystalline SnO2 core surrounded by an amorphous SiOx sheath. The annealing effects on the core-shell nanowires were investigated, revealing that the outer surface became rougher by the thermal annealing. For core-shell nanowires, a room-temperature PL measurement with a Gaussian fitting showed yellow, blue, and violet light emission bands, with the relative intensity of the yellow band showing an increase after thermal annealing. Possible PL emission mechanisms are discussed. This study reveals that the sputtering is effective for preparing the shell layers of nanocables.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
