Evidence of hot electrons generated from an $AlN∕GaN$ high electron mobility transistor

We have observed that the temperature of the electrons drifting under a relatively high electric field in an $AlN∕GaN$-based high-electron-mobility transistor is significantly higher than the lattice temperature (i.e., the hot electrons are generated). These hot electrons are produced through the Fröhlich interaction between the drifting electrons and long-lived longitudinal-optical phonons. By fitting electric field versus electron temperature deduced from the measurements of photoluminescence spectra to a theoretical model, we have deduced the longitudinal-optical-phonon emission time for each electron is to be on the order of $100fs$⁠.