Disappearance of the Breakdown of Quantum Hall Effects in Short Devices

Abstract
Device-length dependence of the breakdown of the integer quantum Hall effects is studied by using devices with narrow constricted regions of different lengths L at T=1.5 – 4.2 K and Landau-level filling factors of ν= 2, 4 and 6. Samples are fabricated from GaAs/AlGaAs heterostructures. Sharp increase in the diagonal resistance R x at a critical current disappears, and is replaced by a continuous and gradual increase in short constricted regions of L < 30 µm. The observed L-dependence supports an avalanche-type carrier multiplication mechanism triggered by electron-superheating.