Hg_(1- x)Cd_x Te禁带宽度附近折射率增强效应(英文)

REFRACTIVE INDEX ENHANCEMENT EFFECT IN Hg_(1-x)Cd_xTe NEAR THE FUNDAMENTAL GAP 

用红外椭圆偏振光谱测量了室温下 Hg1 - x Cdx Te(x=0 .2 76 ,0 .30 9,0 .378)体材料位于禁带宽度之下、附近和之上的折射率 .对每一种组份样品均观察到明显的折射率增强效应 .折射率峰值所对应的能量位置近似等于其禁带宽度 .禁带宽度之上折射率随波长 λ变化可用 Sellmeier色散关系 n2 (λ) =a1 + a2 / λ2 + a3/ λ4+ a4/ λ6进行拟合 .

The refractive indices of Hg1-xCdxTe bulk samples with the composition x = 0.276, 0.309, and 0.378 were measured by infrared spectroscopic ellipsometry at room iemperature in the energy regions which were below, across, and above the fundamental band gap. An obvious refractive index enhancement effect was observed in the refractive index spectra for each composition. The energy position of the maximal refractive index value equals approximately that of the band gap. The refractive index versus wavelength lambda above the band gap for xbetween x = 0.276 and 0.378 was modeled using a Sellmeier dispersion relationship n(2)(lambda)= a(1)+a(2)/lambda (2)+a(3)/lambda (4)+a(4)/lambda (6).