Langevin-Boltzmann approach for fluctuations in a hot-electron-hot-phonon system

A deterministic model for fluctuations in a non-equilibrium bulk electron-phonon system based on the Boltzmann-Langevin equation is used to investigate the influence of nonequilibrium (hot) phonons on electron small signal and noise properties of undoped bulk GaN at room temperature. The discretization of the kinetic equations for the coupled electron-phonon system and stabilization of the Newton-Raphson scheme is discussed. The hot-phonon effect enhances the electron noise temperature and reduces the small signal mobility at a low frequency. The hot-phonon contribution are important above the frequency defined by the hot-phonon lifetime.