Study of the Parameters of a Two-Dimensional Electron Gas in InGaN/GaN Quantum Wells by Terahertz Plasmon Resonance

A new approach to determining the parameters of a two-dimensional electron gas (2DEG) in InGaN/GaN quantum wells is proposed. It is based on terahertz time-domain spectroscopy (THz-TDs), within which the THz frequencies of two-dimensional plasmon resonances excited in the samples of InGaN/AlGaN/GaN heterostructures by femtosecond laser pulses at a wavelength of 797 nm are recorded. The oscillating behavior of the output THz radiation power with minima in the frequency range of 1-5 THz is shown, which is associated with the excitation of plasmon oscillations in a two-dimensional electron gas localized in an InGaN/GaN quantum well. During the processing of THz spectra, the effect of renormalization of the effective mass of 2DEG, as well as phase modulation near the frequencies of plasmon resonances with an increase in the temperature of the sample from 90 to 170 K, is found. The proposed method is contactless and can be used in a wide temperature range.