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RISS 인기검색어
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- 저자 : KANNAPPANSANTHAKUMAR (검색결과 4 건)
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KANNAPPANSANTHAKUMAR,Dong-Wook Kim,Heon Song,Eun-Su Jang,이선호,이철로,M. D. Kim 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.1
Vertically-aligned gallium-nitride nano-columns were grown on a gallium-coated silicon substrate by using molecular beam epitaxy. The dense packing of the nano-columns gives them the appearance of a continuous film in a surface view, but a cross-sectional analysis shows them to be isolated nanostructures possessing a pyramid like tip. The diameter and the length of the GaN nano-columns were about 100 nm and 0.7 - 1 um, respectively. From the photoluminescence measurement of nano- columns, a narrow peak at 363 nm with a full width at half maximum of 63 meV related to excitonic emission was observed. From the Raman spectrum, the phonon peak at 566.9 was assigned to the E2 phonon mode of GaN, which clearly indicates that the GaN nano-columns are well grown. From the above result, it is evident that the grown nano-columns are highly crystalline and are aligned perpendicular to the silicon surface.
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GaN Nano-Column Growth on a Si(111) Substrate by Using a Pt+Ga Alloy Seeding Method with MOCVD
이철로,장은수,이선호,KANNAPPANSANTHAKUMAR,김동욱,김진수,이인환,이주인 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
Gallium-nitride nano-column arrays were grown on a platinum-coated Si(111) substrate by using the Pt+GaN alloy seeding method with metal-organic chemical vapor deposition (MOCVD). Two important growth parameters were considered, the pre-deposition of the Ga source prior to generating the droplets and the droplet formation temperature. The surface morphology and the optical characterization of the grown GaN nano-columns were studied using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and photoluminescence (PL). The SEM image reveals the vertical growth of GaN nano-columns. The growth of the GaN nanocolumns was confirmed by EDX, which indicated that they were composed of gallium and nitrogen. The PL spectrum reveal a sharp peak at 366.7 nm with a full width at half maximum (FWHM) of 160 meV, which clearly indicated that the grown GaN nano-columns were highly crystalline in nature.
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InN Nano-column Grown on a Si (111) Substrate by Using a Au + In Solid Solution Method with MOCVD
이선호,장은수,김동욱,In-Hwan Lee,KANNAPPANSANTHAKUMAR,이철로 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.3
InN nano-columns were grown on Au-coated silicon (111) substrates by using metal organic chemical vapor deposition. Here, the indium pre-deposition was performed before InN nano-column growth. The formation of InN nano-columns was conducted by forming Au + In solid solution droplets on the Au-coated substrate and subsequently nitriding those Au + In droplets. This study investigated the morphological changes in the InN nano-columns due to changes in the growth conditions such as the growth temperature, the trimethylindium (TMI) flow rate and the growth pressure. The scanning electron microscopy (SEM) investigation showed that the InN nano-columns were single crystals with diameters ranging from 90 to 180 nm and lengths of about 2.5 μm. The Raman microscopy spectrum of the nano-columns showed peaks at 495 cm−1 and 594 cm−1, which were assigned to degree what are E2 (high) at 492 cm−1 and A1 (LO) at 596 cm−1 of InN, respectively. In the high-resolution X-ray diffraction (HR-XRD) spectrum diffraction from the (002) plane was observed at 31.315˚
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Growth and Evaluation of GaN Grown on Patterned Sapphire Substrates
Dong-Hun Kang,Eun-Su Jang,Heon Song,Dong-Wook Kim,Jin-Soo Kim,이인환,KANNAPPANSANTHAKUMAR,이철로 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.6
We report the microstructure and the optical properties of gallium nitride (GaN) epilayers grown on a lens-shaped patterned sapphire substrate (PSS) by using metalorganic chemical vapor deposition (MOCVD) for various growth times. The lens shaped pattern was used to reduce the threading dislocation density and to improve the optical emission efficiency. The scanning electron microscope (SEM) image shows a flat and smooth surface for the GaN grown on the PSS for 80 min, which could be achieved by lateral growth from the trench region. From the double crystal X-ray diffraction (DCXRD) spectra, the full width at half maximum (FWHM) value was found to decrease with increasing growth time. The FWHM of the sample grown for 80 min was 473.5 arc sec. This indicates that there is an improvement in the crystalline quality of the GaN grown on the PSS as the growth time increases. From the Raman spectra, the shift of the A1(LO) and E2high phonon mode frequencies towards a higher wavelnumber was observed for GaN grown on PSS as compared to GaN grown on an unpatterned sapphire substrate (UPSS). The high Raman peak intensity of the GaN epilayers using the patterned substrate with a low FWHM indicates that there is an improvement in the quality of the GaN compared to the layer grown on an unpatterned substrate. From the photoluminescence (PL) spectra, an increase in the band edge emission intensity and a decrease in the defect related yellow luminescence were observed for GaN on the PSS as the growth time increased. From the PL spectra, the FWHM was 82.2 meV at a peak position of 363.9 nm for the sample grown for 80 min. It is clearly seen that threading dislocations can be reduced by lateral growth, thereby improving the light emission efficiency by internal light reflection on the lens surface for the GaN grown on the PSS.
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