Behavior of the contacts of quantum Hall effect devices at high currents

• Published in: Journal of applied physics 2004-07, Vol.96 (1), p.404-410
• Main Authors: Meziani, Y. M., Chaubet, C., Bonifacie, S., Raymond, A., Poirier, W., Piquemal, F.
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.1748853

We have analyzed the behavior of contacts of quantum Hall effect devices while increasing the current through the sample. Experiments have been performed in the i=2 plateau, which is used in all metrological measurements of the von Klitzing constant RK, before the onset of dissipation. Using only electrical measurements, we show that a high electric field zone appears in the vicinity of the current contact which injects the electrons in the two-dimensional electron gas, when the current is increased. This heating phenomenon develops in the region close to the source, increases the electronic temperature in the sample, and limits the precision in the measurement of RK. We have studied several samples of different width, using a well-defined configuration for the measurements. It is observed that the threshold current for the onset of the voltage drop across the contact increases with the width of the Hall bar. Consequences for high precision measurements are discussed in terms of experimental protocol and of contact’s geometry.