半导体远红外反射镜中反射率和相位研究

以GaAs材料为例，研究了半导体远红外反射镜中的反射率和相位.通过拟合不同掺杂浓度下样品的远红外反射谱，得到了自由载流子的弛豫时间随掺杂浓度变化的经验公式，并把该规律应用到数值计算中.详细讨论了反射镜的结构和材料参数对反射率R和相位φ的影响.根据腔体内吸收率最高的判据得到了最优的反射镜的参数，并计算了这种优化后的反射镜的波长选择特性.最后，通过远红外反射光谱的测量，从实验上验证了这种反射镜的实际效果. 所得结论为半导体远红外器件中的反射镜设计提供了参考. 关键词： 远红外反射镜 反射率 相位

Reflectivity and phase shift of semiconductor far-infrared mirrors

We have carried out an in-depth investigation on the reflectivity R　and phase shift φ of a novel semiconductor mirror, which can be applied in the far-infrared (FIR) spectral range. By fitting FIR reflection spectra of the GaAs material with different doping concentrations, empirical formulas are obtained for the doping concentration-dependent carrier relaxation time τ of n-GaAs and p-GaAs. The effects of structure and material parameters on the reflectivity and the phase shift of the mirror are analytically studied on the　basis of the deduced formulas. All the related parameters of the mirror are further optimized, and the corresponding wavelength selectivity is calculated according to the highest absorption in the detector cavity. The experimental FIR reflection result confirms the theoretical simulation, revealing the unique properties of this mirror, which establishes the basis of optimum designing of various FIR mirrors.