High-field transport in a dense two-dimensional electron gas in elementarysemiconductors

We calculate the dependence of the electron temperature T and the drift vel ocity v(d) on the applied electric field E for a two-dimensional electron g as in elementary semiconductors. We consider the case of high electron conc entrations when the energy dependence of the electron distribution function is governed by electron-electron collisions. We show that, in the one-vall ey approximation, T should tend to infinity at a certain value of the elect ric field E=E-c. This result is linked to the "runaway" effect, which takes place in the two-dimensional case, even for the deformational phonon scatt ering. Transitions of hot electrons into the upper valleys with larger dens ities of states limit the growth of T. As a result, a two-dimensional elect ron gas should exhibit a negative differential mobility, just as in the pre viously discussed case of noninteracting electrons. (C) 2001 American Insti tute of Physics.