EN
Electron transport in long (up to 15μm) InN n^+nn^+ structures is theoretically investigated by the Monte Carlo particle technique at low lattice temperatures when optical phonon emission is the dominating scattering mechanism. It is shown that at constant bias a free-carrier grating can be formed inside the n-region. Such a grating is found to be responsible for microwave power generation in the THz frequency range. The generation mechanism is similar to that in submicron n^+nn^+ structures under quasiballistic transport conditions.