| AVS 65th International Symposium & Exhibition | |
| Spectroscopic Ellipsometry Focus Topic | Tuesday Sessions |
| Session EL-TuP |
| Session: | Spectroscopic Ellipsometry Focus Topic Poster Session |
| Presenter: | Pablo Paradis, New Mexico State University, Department of Physics |
| Authors: | P. Paradis, New Mexico State University, Department of Physics S. Zollner, New Mexico State University, Department of Physics R. Carrasco, New Mexico State University, Department of Physics J. Carlin, The Ohio State University, Department of Electrical and Computer Engineering V. Dahiya, The Ohio State University, Department of Electrical and Computer Engineering A. Kazemi, The Ohio State University, Department of Electrical and Computer Engineering S. Krishna, The Ohio State University, Department of Electrical and Computer Engineering |
| Correspondent: | Click to Email |
Antimonides are attractive materials for mid-infrared detectors and emitters, because they form a direct band gap, which can be tuned from 0.1 to 0.7 eV. For the design and modeling of such devices, the optical constants of these materials must be known. We present results of Fourier-transform infrared (FTIR) ellipsometry measurements of bulk GaSb and doped and undoped InAsSb alloys with different compositions. Doped and undoped layers of InAsSb alloys were grown on GaSb substrates by MOCVD. Their optical constants were determined using two different methods. First, we fitted the data as a sum of oscillators representing the free-carrier and interband optical response, which allows a physical interpretation of the results. Second, we expanded the dielectric function into a sum of Kramers-Kronig consistent B-spline polynomials, assuming thicknesses obtained from the growth parameters. In the doped layers, a free-carrier reflectance band can clearly be seen in the spectra, while the undoped layers show an absorption increase at the band gap. The 10% Sb samples are lattice matched and the 44% Sb samples are lattice mismatched leading to some strain inhomogeneity in the samples. This can be seen in the dielectric function of these samples. In the doped samples, we analyze the optical conductivity obtained from parametric oscillator fit. We pay attention to the plasma frequency term in our parameters to describe the behavior of the conductivity in doped vs undoped layers.