▎ 摘　　要

NOVELTY - Graphene hall sensor (10) comprises a substrate (18), an encapsulating layer (20) formed on a graphene sheet provided on the substrate, a dielectric layer or alumina layer (12) provided on the graphene sheet. The graphene sheet and the dielectric layer share a continuous outer edge surface, a first pair of electrical contacts (14, 15) in electrical contact with the graphene sheet and spaced apart along a first direction, and a second pair of electrical contacts (16, 17) in electrical contact with the graphene sheet and spaced apart along a second direction. The first direction is perpendicular to the second direction, a path along the first direction between the first pair of electrical contacts crosses a path along the second direction between the second pair of electrical contacts, and the graphene sheet has a sheet carrier density in the range of 2x1011 cm-2 to 1x1013 centimeter-square (cm-2). USE - Graphene hall sensor is used for operation at cryogenic temperatures to measure magnetic fields from 3-22 Tesla (T) at cryogenic temperatures of less than 120 Kelvin. ADVANTAGE - The separation of the charge carriers across the conductor establishes an electric field that opposes further charge separation. This potential is the Hall voltage, which can be measured across the conductor. Thus, measurement of the Hall voltage allows the magnetic field to be determined. The Hall sensor has improved sensitivity. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: (1) a graphene Hall sensor array for operation at cryogenic temperatures, which comprises a substrate, a graphene sheet provided on the substrate, the graphene sheet having a plurality of discontinuous graphene portions, each discontinuous graphene portion defining a graphene Hall sensor of the graphene Hall sensor array, a dielectric layer provided on the graphene sheet, the dielectric layer having a set of discontinuous dielectric portions provided on the discontinuous graphene portions, where each discontinuous graphene portion of the graphene sheet and a corresponding discontinuous dielectric portion share a continuous outer edge surface; (2) a magnetic field measurement system, which comprises a graphene Hall sensor, and a Hall measurement controller connected to the first and second pairs of electrical contacts, the Hall measurement controller configured to perform a Hall-effect measurement using the graphene Hall sensor; (3) a method of determining a magnetic field at cryogenic temperatures, which involves (a) exposing a graphene Hall sensor to a cryogenic environment having a temperature of no greater than about 120 K, and (b) performing a Hall-effect measurement using the graphene Hall sensor; and (4) a method of manufacturing a graphene Hall sensor, which involves (a) forming a graphene sheet on a substrate, (b) patterning a plasma-resistant dielectric layer onto a portion of the graphene sheet to form an intermediate having at least one covered region and at least one uncovered region of the graphene sheet, (c) subjecting the intermediate to plasma-etching, where the at least one uncovered region of the graphene sheet is etched away to form an etched layer structure having one or more exposed edge surfaces, (d) forming a first pair of electrical contacts in electrical contact with the graphene sheet and spaced apart along a first direction, and (e) forming a second pair of electrical contacts in electrical contact with the graphene sheet and spaced apart along a second direction, where the first direction is perpendicular to the second direction and where a path along the first direction between the first pair of electrical contacts crosses a path along the second direction between the second pair of electrical contacts, and the graphene sheet has a sheet carrier density in the range of 2x1011 cm-2 to 1x1013 cm-2. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a graphene Hall sensor Graphene hall sensor (10) Dielectric layer or alumina layer (12) First pair of electrical contacts (14, 15) Second pair of electrical contacts (16, 17) Substrate (18) Encapsulating layer (20)