Temperature Dependence of Refractive Indices of InP, GaAs, AlAs, and In0.53Ga0.47As in the Midinfrared Spectral Range Determined by Combined Ellipsometry and Fourier-transform Spectroscopy

We present the results of Fourier-transform measurements for determination of refractive indices of four semiconductor alloys in the midinfrared spectral range from 10 to 300 K. We investigate double-sidedpolished, undoped InP and GaAs substrates as well as In0.53Ga0.47As/InP and AlAs/GaAs distributed Bragg reflector (DBR) mirrors with their operational wavelength designed for 4 mu m. Through analysis of measured transmittance spectra supported by ellipsometry it is possible to determine the temperaturedependent refractive indices of InP and GaAs from 1.3 to 11 mu m. Furthermore, by using reflectivity measurements supported by numerical modeling of the two types of designed DBR structures the refractive indices of In0.53Ga0.47As and AlAs for around 4 mu m are determined with their temperature dependencies. Data acquired through this method could lead to improvement of already existing optical semiconductor devices expanding their application for longer wavelengths.