A new generation of QHARS: discussion about the technical criteria for quantization

Abstract

New quantum Hall array resistance standards (QHARS) with nominal values in the range from R K /200 to 50R K (i = 2 plateau) have been developed (R K is the von Klitzing constant). The design of the QHARS based on the connection in parallel of Hall bars is made suitable for use in both magnetic field directions. Measurements performed with currents up to 4 mA at 1.3 K show that R K /200 (∼129 ) and 16R K /4130 (∼100 ) resistance standards have Hall resistances which agree with their nominal values within 5 parts in 10 9 (1σ ). While increasing the temperature, the Hall resistance varies linearly with the longitudinal resistance. Because the sign of this deviation depends on the magnetic field direction, the average of the Hall resistance values measured for both magnetic field directions remains constant within 5 parts in 10 9 up to 4.2 K. Owing to their large working current, these QHARS have allowed an accurate calibration of a 100 wire resistor using a commercial resistance bridge. An R K /20 (∼1290 ) resistance standard made of ten Hall bars placed in parallel by quadruple connections has also been studied. It is found that the resistances measured by using three different voltage terminal pairs agree within 5 parts in 10 9 in relative value.

Mini array of quantum Hall devices based on epitaxial graphene

“…Each of the four Hall bars on the chip has the possibility for independent connection and measurement of the Hall voltage at potential terminals on the sides of the Hall bar. Additional cross connections serve to suppress the influence of the non-negligible contact resistance of interconnections on the serial Hall voltage [14,15]. These connections have been made using Al bonding wire with the resistance of each wire about 10 mΩ.…”

Quantum Hall Effect and Ohm Metrology

“…6a shows the picture of a QHARS129 sample. 25 It is composed of 100 Hall bars, 200 µm large, placed in parallel by triple connections. The quality of the layer which ensures the electrical insulation between the two levels of gold connections is particularly crucial: any short-circuit due to pinholes makes the device unusable.…”

Development of QHR arrays in NIM

“…Several metrology institutes have fabricated QHARS of different resistance values based on the AlGaAs/GaAs heterostructure [1][2][3]. In this paper we present our effort towards the quantum Hall array device.…”