Mini array of quantum Hall devices based on epitaxial graphene

Abstract

Series connection of four quantum Hall effect (QHE) devices based on epitaxial graphene films was studied for realization of a quantum resistance standard with an up-scaled value. The tested devices showed quantum Hall plateaux R H,2 at filling factor ν = 2 starting from relatively low magnetic field (between 4 T and 5 T) when temperature was 1.5 K. Precision measurements of quantized Hall resistance of four QHE devices connected by triple series connections and external bonding wires were done at B = 7 T and T = 1.5 K using a commercial precision resistance bridge with 50 μA current through the QHE device.The results showed that the deviation of the quantized Hall resistance of the series connection of four graphene-based QHE devices from the expected value of 4×R H,2 = 2h/e 2 was smaller than the relative standard uncertainty of the measurement (< 1×10 -7 ) limited by the used resistance bridge.

Epitaxial graphene for quantum resistance metrology

“…These results demonstrate the feasibility of p-n junctions for metrology but also show the need of further development with respect to gating or doping techniques that allow for the design of more complex devices that are capable of scaling within a wide range of resistance values with assured high accuracy. Similar implementations of multiple graphene devices have been suggested for use with ac-resistance scaling methods [83].…”

Atypical quantized resistances in millimeter-scale epitaxial graphene p-n junctions

“…One approach to reaching this goal includes creating quantum Hall arrays. [17][18][19] A major disadvantage to this approach is the requirement that many individual Hall bar devices be connected using a network of resistive interconnects, thereby increasing the total minimum device size and possibly lacking optimal contact resistances. The second approach involves building p-n junctions (pnJs) that operate in the quantum Hall regime, as has been previously demonstrated in EG with lateral dimensions on the order of 100 μm.…”

Two-Terminal and Multi-Terminal Designs for Next-Generation Quantized Hall Resistance Standards: Contact Material and Geometry

“…QUANTUM effects in epitaxial graphene (EG) devices allow for robust quantum Hall effect (QHE) resistance plateaus at R H = R K /2 =h/2e 2 , where R H is the Hall resistance, and R K is the von Klitzing constant [1]- [3]. By using series and parallel connections as building blocks, we can construct quantum Hall array resistance standards (QHARS) that provide multiple quantized resistance values [4]- [9]. However, resistance networks based on multiple quantized Hall resistance (QHR) devices often suffer from accumulated resistances at contacts and interconnections.…”