NONLINEAR CURRENT-VOLTAGE CHARACTERISTIC IN NARROW CHANNELS AND LOW-VOLTAGE BREAKDOWN OF THE QUANTUM HALL-EFFECT

The current-voltage characteristic (CVC) and the breakdown of the quan tum Hall effect (QHE) are considered in narrow quasi-two-dimensional c hannels subject to a strong perpendicular magnetic field B. The intera ction of electrons with acoustical and piezoelectrical phonons leads t o electron transitions at the edges of the channel and to the main dis sipation if the channel width W is not too large. Nonheating negative differential conduction (dj(x)/dE(x) < 0), when an electric field E(x) is applied along the channel, is possible for drift velocities v(D) s maller, much smaller, or larger than the speed of sound s. The CVC j(x ) = j(x)(E(x)), is substantially nonlinear if v(D) is not too small. T he results agree with the observations [1] (v(D) similar to s/20) in m etal-oxide-semiconductor (MOS) structures. The observed exponential in crease in the dissipation before breakdown [2], by two orders of magni tude, is explained as well. The anisotropy of the electron-phonon inte raction in MOS structures and its substantial influence on the CVC and v(D) is also considered.