Infrared spectroscopic ellipsometry of Ge-doped SbTe alloys

We grew Ge-SbTe films on glass substrates using RF sputtering deposition. We measured the dielectric function of the Ge-doped SbTe thin films in the infrared and visible spectral region. By applying linear extrapolation to the absorption coefficient, we obtained accurate band gap energy values, which decreased with increasing Te composition. Using the Drude model, we estimated their resistivity and mean scattering time. Compared to the Hall effect parameters of carrier concentration and mobility, we estimated the effective mass of holes for the Ge-SbTe thin films.