Redefining Hall-Effect sensors with graphene: Page 3 of 5

July 25, 2020 //By Simon Thomas, Paragraf
Analysis of a wafer of graphene Hall-Effect sensors
A new graphene manufacturing process is opening up opportunities for Hall-Effect sensors says Simon Thomas, CEO of Paragraf
substrate, most commonly a copper foil. Graphene fabricated in this way needs to be transferred onto an electronics compatible substrate afterwards. There are several different transfer processes that can be employed for that purpose - though none is ideal. They can potentially impinge on how the graphene functions in an electronic device, by either contaminating the graphene or damaging its structure.

For many of the transfer processes it is simply not possible to remove all the copper atoms. The chemicals used in wet transfer processes can also remain present too. These metallic impurities and chemical contaminants have a detrimental effect on the graphene properties and hence any subsequent device performance. Conversely ‘dry’ transfer methods can result in defects within the graphene itself - the quality of the graphene is thus not of the expected standard and the full benefits of its properties cannot be realised.

Wire bonding a graphene Hall-Effect sensor to a package 

A New Approach to Fabricating Graphene

A scalable process has been developed to produce single-atom thick layers directly onto widely-used crystalline semiconductor wafer substrates - such as silicon (Si), silicon-carbide (SIC), sapphire and gallium-nitride (GaN). Consequently, the contamination issues that transfer activities cause can be circumvented, with the upshot that commercially viable devices incorporating graphene may be produced in volume.

The graphene produced by this method can cover a wide area (addressing full size 8-inch wafers), with much better uniformity. Also, reproducibility is assured, so there will be minimal variation in end product quality, and the process is compatible with existing electronic device manufacturing procedures and equipment. Furthermore, while other graphene production/transfer processes mean there is little flexibility, the ground-breaking Paragraf process permits the electrical and mechanical properties of the manufactured graphene to be tuned at the point of production. Inclusion of expensive post-processing techniques can thus be avoided.

Graphene Hall-Effect Sensors

The Hall-Effect sensors produced using this proprietary process have set new performance benchmarks. As

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