2DEG magnetic imaging sensors

DC Digital Hall Effect Integrated Circuit (Dimension = 1× 1.1mm)
Figure 1 - DC Digital Hall Effect Integrated Circuit (Dimension = 1× 1.1mm)

Commercial Integrated Hall devices are fabricated using Silicon CMOS which has limited sensitivity but benefit greatly from integrated electronics. We have developed a new type of integrated sensor (based on GaAs-InGaAs-AlGaAs) which utilises a two Dimensional Electron Gas (2DEG) system with high electron mobility and moderate sheet carrier densities to synthesise both magnetic and circuit functionalities in a similar manner to CMOS Hall ICs. Process Development Kits (PDK) which include all the elements required for successful integration have been developed in an effort to design and fabricate both digital and analogue integrated Hall ICs with unprecedented sensitivities and outstanding operating temperature ranges.

The first 2DEG GaAs-InGaAs-AlGaAs monolithic all Integrated DC Digital Hall Effect Circuit with superior temperature characteristics has been developed (Figure 1). This IC is capable of detecting DC magnetic fields as low as 6mT and can operate at temperatures up to 200°C. Existing Digital Hall ICs, all based on Silicon, can only operate at temperatures up to 150°C.               

AC Linear Hall Effect Integrated Circuit
Figure 2 - AC Linear Hall Effect Integrated Circuit

To take advantage of reduced 1/f noise at higher frequencies, an entire GaAs-InGaAs-AlGaAs based AC Linear Hall Effect Integrated Circuit has also been developed (Figure 2). This IC with a sensitivity of 0.52µV/nT and power consumption of 6.4mW is capable of detecting magnetic fields as low as 177nT at frequencies in the range of 1 to 200 kHz.

The most sensitive commercial Linear Hall IC using Silicon technology provides a minimum detection field of 650nT (Figure 3).

Minimum Detectable Field, Comparison with Allegro, Honeywell and Melexis
Figure 3 - Minimum Detectable Field, Comparison with Allegro, Honeywell and Melexis
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