High resolution magnetic microscopy based on semi-encapsulated graphene Hall sensors

Abstract

The realization of quantitative, noninvasive sensors for ambient magnetic imaging with high spatial and magnetic field resolution remains a major challenge. To address this, we have developed a relatively simple process to fabricate semi-encapsulated graphene/hBN Hall sensors assembled by dry transfer onto pre-patterned gold contacts. 1 μm-sized Hall cross sensors at a drive current of 0.5 μA exhibit excellent room temperature sensitivity, SI ∼ 700 V/AT, and good minimum detectable fields, Bmin = 0.54 G/Hz0.5 at a measurement frequency of 1 kHz, with considerable scope for further optimization of these parameters. We illustrate their application in an imaging study of labyrinth magnetic domains in a ferrimagnetic yttrium iron garnet film.

Mitigation of Device Heterogeneity in Graphene Hall Sensor Arrays Using Per-Element Backgate Tuning

“…The CMOS compatibility of GHSs has been shown by hybrid integration demonstrations. , Graphene Hall sensors reported in the literature exhibit high sensitivity ( R H ∼ 2.1 kΩ T –1 for CVD graphene devices) comparable with III–V sensors ( R H ∼ 1.1 kΩ T –1 for similarly sized GaAs devices). The effects of graphene preparation, geometry, and encapsulation on GHS performance have been well characterized. − Other recent work has applied these devices to scanning magnetometry , and microfluidic biosensing applications. , …”

“…The effects of graphene preparation, geometry, and encapsulation on GHS performance have been well characterized. 25−27 Other recent work has applied these devices to scanning magnetometry 28,29 and microfluidic biosensing applications. 30,31 A major limitation of graphene Hall sensors is their performance heterogeneity, which includes variability between graphene Hall devices on the same chip, batch-to-batch variation, and device drift over time (Figure 1A).…”