With single quantum-Hall-devices, and by virtue of the relation Rn=h/(
ne²), the values of resistance R2=12,9 kΩ and R4= 6,45 kΩ can be realised with extremely low uncertainties and be utilised for calibrations. In order to transfer this low uncertainty to the numerous resistance values in practical use in industry elaborate measurement transfer chains are normally employed.
They can be avoided when individual quantum Hall devices are connected as networks of parallel and series resistances since this allows to build in principle arbitrary resistance values. In spite of the inevitable interconnect resistances the fundamental precision of the quantum standard is maintained due to a special connection scheme which was demonstrated in the early 90ies by F. Delahaye at the French national metrology institute.
The production of the integrated quantum Hall devices imposes some additional requirements both during the growth of the semiconductor wafer and during the actual creation of the integrated device. In the material growth stage it is important to produce a very homogenous density of electrons across a wafer since the total integrated device area is distinctly larger than for a single element. During the technology steps for integration both the necessary multi-layer technology and the quality and yield of the contacts pose the largest challenges which will to be solved with the modern facilities in PTB’s clean room centre.
