Electrically-controlled THz emission from AlGaN/GaN/Al2O3 high electron mobility transistor structures at a temperature of 20 K

we investigated radiative phenomena contributing to the THz emission of AlGaN/GaN high electron mobility transistor (HEMT) structures grown on sapphire substrate. Electrically controlled emission spectroscopy was performed in the frequency range 100–600 cm-1 at a temperature of 20 K. The electroluminescence from nitrogen vacancies in GaN buffer layer contributed to the THz emission spectrum, and the amplitude and frequency of the observed narrow emission lines were controlled by applied voltage.