Runaway effects in nanoscale group-III nitride semiconductor structures - art. no. 113207

We have revisited the problem of electron runaway in strong electric fields in polar semiconductors focusing on nanoscale group-III nitride structures . By developing a transport model that accounts for the main features of el ectrons injected in short devices under high electric fields, we have inves tigated the electron distribution as a function of electron momenta and coo rdinates. Runaway transport is analyzed in detail. The critical field of th is regime is determined for InN, GaN, and AIN. We found that the transport in the nitrides is always dissipative (i.e., no ballistic transport). For t he runaway regime, however, the electrons increase their velocities with di stance, which results in average velocities higher than the peak velocity i n bulklike samples. We have demonstrated that the runaway electrons are cha racterized by a distribution function exhibiting a population inversion.