Evaluation of AlGaAs/GaAs two dimensional electron gas heterostructures to obtain a resistance standard

The quantum Hall Effect allows to the national metrology institutes to reproduce the unit of resistance (ohm) in terms of physical constants. We have made efforts in order to develop AlGaAs/GaAs heterostructures with enough quality to be used in metrology as a resistance standard. The ohmic contacts in the samples is one of the most important aspects for metrology applications, therefore good contacts are essential in the analysis of the longitudinal resistance under dissipationless condition. Measurements at 1.3 K temperature, in magnetic fields up to 12 T were made, as required to obtain Quantum Hall Effect phenomenon. Our results show that the developed samples have low longitudinal resistance, comparable with those used at the Mexican national metrology institute as reference standard of dc resistance.