The Quantum Hall Effect and Resistance Standards

Following the discovery of the quantum Hall effect in 1980 metrologists were eager to develop the effect as a resistance standard in a similar manner to the development, a decade earlier, of the Josephson effects in superconductors as a voltage standard. This article reviews the progress made by many national laboratories to assess and compare the quality and limitations of semiconductor devices, mainly silicon MOSFETs and GaAs/AlGaAs heterostructures, as quantized Hall resistance standards with values R H ( i ) = R K / i = h/ie 2 , where R K = 25812,807 Ω is the von Klitzing constant and i is an integer. Potentiometric and cryogenic current comparator bridge techniques for the measurement of R K in terms of conventional resistance standards with 1 σ relative accuracies better than 1 part in 10 8 are compared, and determinations of R K in ohms with accuracies as high as 2,4 parts in 10 8 using calculable capacitors are described. The comparison of direct determinations of R K with alternative derivations of h/e 2 leading to the CCE recommendations and subsequent international adoption, from 1 January 1990, of the value 25812,807 ± 0,005 Ω for R K are also described.