Terahertz studies of carrier dynamics and dielectric response of n-type, freestanding epitaxial GaN

Abstract
We report the characterization of the complex conductivity and dielectric function of GaN by terahertz time-domain spectroscopy. Transmission measurements are performed on an n-type, 180-μm-thick, freestanding GaN crystal. Frequency dependent electron dynamics, power absorption and optical dispersion are observed over the frequency range from 0.1 to 4.0 THz. The measured conductivity is well fit by Drude theory.