Plasmon-assisted power dissipation in GaN-based 2DEG channels for power HFETs

A nitride heterostructure field-effect transistor (HFET) is among the most promising hf power devices. A two-dimensional electron gas (2DEG) channel for the HFET contains a high density of electrons and operates at high electric fields. The main path of power dissipation emission of longitudinal optical (LO) phonons by hot electrons, the nonequilibrium (hot) LO phonons convert into acoustic modes, and the acoustic phonons drain the heat out of the channel. The conversion of hot phonons into acoustic modes is the "bottleneck". A faster conversion would reduce hot-phonon effects and improve frequency performance of the channel. The report discusses the plasmon-assisted hot-phonon conversion in GaN-based 2DEG channels. The experimental technique exploits hot-electron fluctuations - they serve as "fingerprints" of the ultrafast processes of power dissipation.