BREAKDOWN OF THE QUANTUM HALL-EFFECT AS A FUNCTION OF THE FILLING FACTOR AND THE CONTACT CONFIGURATION

The filling-factor dependence of the critical current of the quantum Hall effect (QHE) was measured using several current and voltage contact configurations on Si metal-oxide-semiconductor and Si metal-nitride-oxide-semiconductor Hall bars and Corbino rings. The results indicate that the breakdown is dominated by different mechanisms in different current and filling-factor regimes. The critical current is primarily dependent on the position of the current-injecting contact with respect to the Hall field polarity. At higher currents the data cannot be explained by an edge channel picture. Estimates on the basis of several breakdown mechanisms and calculations based upon a Zener tunnelling model were made to explain the experimental results. The Zener tunnelling model provides the best quantitative results if a filling-factor-dependent width of the quantum Hall current path is introduced. The current path width is maximal near integer filling factors and decreases with deviation from the plateau centre. Our results confirm that the breakdown of the QHE is a local phenomenon.