Ellipsometric studies at and below energy gap on polycrystalline calcium and strontium thiogallates
Ellipsometric studies at and below energy gap on polycrystalline calcium and strontium thiogallates
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多晶硫代镓酸钙和硫代锶在能隙及以下的椭圆光度研究
DOI：
10.1002/pssa.200306635
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
N. Yamamoto
中科院分区：
文献类型：
--
作者：
N. Mamedov;H. Toyota;Atsushi Yasunaka;Y. Shim;A. Kato;A. Ashida;S. Iida;N. Yamamoto
利用光谱位相调制椭偏仪在室温下对不同尺寸的CaGa2、S 4和SrGa2 S 4进行了能隙和能隙以下的宽光子能量范围内的研究。利用扫描电子显微镜和X射线衍射仪对样品进行了表征。与光波长相比，大颗粒样品的伪介电函数是相当合理的。CaGa2和S 4的直接跃迁能隙估计为∼4.10 eV。对于颗粒尺寸较小的样品(∼为10 0 nm)，在衍射光和几何光学的过渡光谱范围内，观察到了主角和最小椭圆角之间的分裂，这不能归结为吸收。
The CaGa 2 S 4 and SrGa 2 S 4 with various grain sizes were studied over a wide range of photon energies at and below energy gap by using a spectroscopic phase modulated ellipsometer at room temperature. Complimentary, SEM and XRD techniques were applied. The pseudo-dielectric function of the samples with large grain sizes as compared to the light wavelength was found to be fairly reasonable. The energy gap for direct transitions in CaGa 2 S 4 was estimated at ∼4.10 eV. For samples with small grain sizes (∼100 nm), a splitting between principle angle and angle of minimal elliptic ratio, that could not be assigned to absorption was observed in the transient spectral range between diffraction and geometric optics.