Zn-doped GaSb epitaxial film absorption coefficients at terahertz frequencies and detector applications

The reflectance measurements of p-type GaSb:Zn epitaxial films with different hole concentrations, grown by metalorganic vapor-phase epitaxy, have been investigated in the 3–30-THz frequency region. The experimental spectra were fitted using a classical harmonic Lorentz oscillator and the Drude model, illustrating that the hole effective mass and the mobility change with the carrier concentration. The hole effective mass was found to vary from 0.22m0 to 0.41m0 as the carrier concentration changed from 3.5×1017 to 3.8×1018cm−3. The mobility values derived from the reflectance measurements were slightly smaller than the values obtained from Hall-effect measurements. A sublinear relationship between the absorption coefficient and the hole concentration was found at a frequency of 3 THz. Those results can be used for designing GaSb-based terahertz detectors.