Fourier-transformed photoreflectance and fast differential reflectance of HgCdTe layers. The issues of spectral resolution and Fabry–Perot oscillations

Fourier-transformed photoreflectance and fast differential reflectance (FDR) spectroscopies have been used to investigate the optical properties of HgCdTe layers of various compositions that spectrally target a broad range of mid and long infrared wavelengths. For this spectral range, the extraordinary sensitivity of these modulation techniques has allowed for direct measurement of the fundamental band gap as a function of temperature and Cd-atom concentration. Additionally, employing the FDR technique has allowed us to detect the absorption-like spectra in this long-wavelength range within a collection time of less than 1 min. Finally, it is seen that, in order to obtain an unequivocal interpretation of the experimental data from Fourier-spectrometer-based measurements of differential reflectivity, a proper selection of the spectral resolution and number of scans is crucially important