Exploring the Optical Properties of Hg1−xCdxSe Films Using IR-Spectroscopic Ellipsometry
We have used infrared spectroscopic ellipsometry to interrogate the dielectric response of a series of Hg1−xCdxSe samples in a spectral range between 2000 and 40000 nm. Using a standard inversion technique, the experimental data obtained at multiple angles of incidence were modeled to deduce the dielectric function of each sample. The dielectric functions obtained for Hg1−xCdxSe samples allowed us to predict the band gaps for the samples, which increase as a function of the Cd concentration. Next, we modeled the dielectric function as a collection of oscillators, each of which represented a particular transition manifested in the spectrum. The most significant result obtained from this work is the recovery of their doping characteristics from the ellipsometric data. Specifically, two Hg1−xCdxSe samples with x = 0.21 and 0.28, grown on GaSb substrates, show a carrier concentration of 1.6 × 1017 and 1.8 × 1018 cm−3, respectively. These results are particularly helpful because conventional Hall measurements cannot be used for these specific samples due to the substrates (i.e., GaSb) used to grow them being highly conductive.
Peiris, F., Brill, G., Doyle, K. et al. Journal of Elec Materi (2014) 43: 3056. doi:10.1007/s11664-014-3208-0
Journal of Electronic Materials