Terahertz Time-Domain Spectroscopy (THz-TDS) of LED Heterostructures with Three and Five InxGa1 – xN/GaN Quantum Wells

Using terahertz time-domain spectroscopy (THz-TDS), we have detected resonance frequencies of plasmon oscillations excited in heterostructures with multiple InxGa1 – xN/GaN quantum wells by laser pulses with a duration of 130 fs in the temperature range from 90 to 170 K. The fast Fourier transform of temporal forms of terahertz pulses has made it possible to obtain frequency spectra of the power and of the phase shift of terahertz radiation, the interpretation of which has allowed us to estimate the quasi-momentum relaxation time (τ = 10–12 s), mobility (μ = 4 × 103 cm2/(V s)), and effective mass (m* = 0.45m) of majority charge carriers in these heterostructures. Based on the frequency spectra of power and phase shift of terahertz radiation, we have obtained the temperature dependences of the effective mass and relaxation time of the quasi-momentum of a 2D electron gas (2DEG). The 2DEG mobility value obtained by the THz-TDS method is in good agreement with the Hall measurement data.