Z.El-Gohary
,
M.El-Nahass
,
H.Soliman
,
Y.L.El-Kady
材料科学技术（英文）
The different optical dispersion parameters of SrLaAlO4 single crystals have been studied by the transmission and reflection measurements at normal incidence for the three orientations 001, 100 and 101 in the spectral range 400nm-2500nm.The optical absorption data revealed the existance of allowed indirect and direct transition. The refractive index has abnormal behaviour in the spectral region 400-900nm, but has a normal one in the higher wavelength region. The optical dispersion parameters, the single oscillator energy Eo and the dispersion energy Ed were determined and indicated the ionic structure of the material. The high-frequency dielectric constant, the lattice dielectric constant and the electronic polarizability were determined by the free carriers and the lattice vibration modes. The real dielectric constant ε1 the dielectric loss tangent (tanδ), the volume (VELF) and the surface energy loss function (SELF) have also been discussed.
关键词:
Optical parameters
,
null
,
null
Z.El-Gohary
,
A.Abdel-Aal
,
A.Elshafie
材料科学技术（英文）
Several thin films of Te10Ge10Se77Sb3 chalcogenide glass of different thicknesses (250nm to 400nm) were prepared by thermal evaporation under vacuum of 133 ×10-6 Pa(10-6torr). X- ray diffraction analysis showed the amorphicity of the prepared films which become partially crystalline by annealing. Transmittance and reflectance measurements in the spectral range of 200nm to 2500nm have been carried out at normal incidence. The analysis of the absorption coefficient data showed the existence of indirect transition for the photon energy E in the range 1-3eV and direct transition for E>3eV. From the determination of the optical constants (n, k), the dispersion of the refractive index has anomalous behaviour in the region of the fundamental absorption edge, and followed by the single- effective oscillator approach.The investigated optical parameters such as the optical energy gap Eopt, the high frequency dielectric constant eoo ,the oscillator position lo, and the oscillator strength So, were significantly affected by the film thickness. The characteristic energy gap obtained from the conductivity measurements is nearly half the value of that obtained from the optical data as in the case of thickness 400nm. The activation energy is 0.65 eV and the indirect optical gap is 1.32eV.
关键词:
Chalcogenide glasses
,
null
,
null
李文连
液晶与显示
doi:10.3969/j.issn.1007-2780.2002.01.005
通过比较有机EL与无机EL、LCD在平板显示应用方面的差异,展示了OELD的美好应用前景.由于无机薄膜EL缺乏高亮度蓝基色成分以及驱动电压是100V左右的交流,难于制成低压彩色超薄显示器;无机分散型EL屏采用的是十几微米厚的粉末材料,也难于制成高分辨率超薄显示器,因此它们都无法与OELD相比.OELD显示器体积可以是LCD的1/2,功耗也大大低于LCD,所以OELD将有望取代LCD.评述了当前OELD的最新发展趋势:采用荧光染料掺杂式的模糊界面结构的电致荧光器件和采用荧光染料掺杂式的电致磷光器件是当前OELD发展的主要潮流.文中还评述了采用低折射率材料提高外量子效率的情况.
关键词:
电致发光
,
磷光
,
发光平板显示
