Graphene's Quantum Properties Break Down Unevenly, Limiting Device Performance
Researchers discovered that tiny pockets of high-density electrons disrupt graphene's quantum Hall effect at high currents, causing resistance to oscillate unpredictably. The finding explains why graphene devices underperform in extreme conditions and suggests engineers must account for these microscopic imperfections when designing next-generation electronics.
Originaltitel: Puddle-Induced Resistance Oscillations in the Breakdown of the Graphene Quantum Hall Effect
<p>We report on the stability of the quantum Hall plateau in wide Hall bars made from a chemically gated graphene film grown on SiC. The v = 2 quantized plateau appears from fields B similar or equal to 5 T and persists up to B similar or equal to 80 T. At high current density, in the breakdown regime, the longitudinal resistance oscillates with a 1/B periodicity and an anomalous phase, which we relate to the presence of additional electron reservoirs. The high field experimental data suggest that these reservoirs induce a continuous increase of the carrier density up to the highest available magnetic field, thus enlarging the quantum plateaus. These in-plane inhomogeneities, in the form of high carrier density graphene pockets, modulate the quantum Hall effect breakdown and decrease the breakdown current.</p>