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SnSe/BaF<sub>2</sub> 단결정 박막의 성장과 광학적 특성
이일훈,두하영,Lee, II Hoon,Doo, Ha Young 한국안광학회 2002 한국안광학회지 Vol.7 No.2
본 실험에서는 HWE 방법으로 성장시킨 SnSe 단결정 박막에 대한 특성을 조사하였다. 성장된 박막의 결정 구조와 격자 상수를 알아보기 위하여 X-ray diffraction(XRD)에 의한 회절 패턴을 측정하고, 단결정 박막의 결정성을 확인하기 위하여 double crystal X-ray diffraction(DCXRD)에 의한 회절 패턴을 측정하여, 원료부와 열벽부 그리고 기판의 온도 변화에 따른 반치폭을 알아보았다. Rutherford back scattering(RBS)을 측정하여 Sn과 Se의 조성비를 확인하고, 실험값과 이론값의 차이를 조사하였다. 박막의 표면 상태는 atomic force microscopy(AFM) 사진과 주사 전자 현미경(SEM) 사진으로 관찰하여 결정구조와 성장 온도와의 연관성을 조사하였다. 광학 상수는 Spectroscopic Ellipsometry(SE) 방법을 이용하여 단결정 박막의 굴절률(n), 유전상수(${\varepsilon}$), 반사율(R) 그리고 흡수 계수(${\alpha}$) 등 광학 상수를 측정했다. This study investigated the crystal growth, crystalline structure and the basic optical properties of $SnSe/BaF_2$ epilayers. The SnSe epilayer was grown on $BaF_2$(111) insulating substrates using a hot wall epitaxy(HWE) technique. It was found from the analysis of X-ray diffraction patterns that $SnSe/BaF_2$ epilayer was growing to single crystal with orthorhombic structure oriented [111] along the growth direction. Using Rutherford back scattering(RBS), the atomic ratios of the SnSe was found to be stoichiometric, almost 50 : 50. The best values for the full width at half maximum (FWHM) of the DCXRD was 163 arcsec for SnSe epilarer. The epilayer-thickness dependence of the FWHM of the DCXRD shows that the quality of the $SnSe/BaF_2$ is as expected. The dielectric function ${\varepsilon}$(E) of a semiconductor is closely related to its electronic energy band structure and such relation can be drawn from features around the critical points in the optical spectra. The real and imaginary parts(${\varepsilon}_1$ and ${\varepsilon}_2$) of the dielectric function ${\varepsilon}$ of SnSe were measured. These data are analyzed using a theoretical model known as the model dielectric function(MDF). The optical constants related to dielectric function such as the complex refractive index(n*-n+ik), absorption coefficient (${\alpha}$) and normal- incidence reflectivity (R) are also presented for $SnSe/BaF_2$.
Cr,Cu,Fe가 첨가된 MgO 단결정의 열자극 발광 스펙트럼 분석
田耕南,兪昇喆,杜夏榮,李春鎬 全北大學校 1994 論文集 Vol.38 No.-
On the MgO single crysital doped artificially with Cr, Cu, Fe we observed thermally stimulated luminescence(TSL) glow curves and spectra, and analyzed them in the temperatured range from 500 to 77 k after excitation with UV or X-ray irradiation. TSL glow curves obtained from these samples show five peaks at 136.5K, 223.5 K, 390 K, 440 K, and their estimated activation energies are 1.08 eV, 0.27 eV, 0.63 eV, 1.19 eV, and 1.33 eV, respectively. When we measured TSL spectrum at the range of 200 nm to 650 nm, we also analysed the peak wavelength which obtained at 345 nm, 375 nm, and 410 nm from measurement of TSL spectrum and described their luminescence mechanisms.