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• A highly sensitive bulk silicon carbide pressure sensor was fabricated using a laser scribing method. • The sensor's sensitivity was obtained to be 10.83 mV/V/bar at 198 K and 6.72 mV/V/bar at 473 K. • The sensor shows a twofold increment of sensitivity in comparison with other silicon carbide pressure sensors. • The as-fabricated sensor exhibits excellent sensitivity, linearity and reproducibility from cryogenic to elevated temperatures.

This paper presents highly sensitive pressure sensors using piezoresistive nanowires. Our approach is based on nanowires locally fabricated on free standing structures with a high strain concentration. This strain concentration phenomenon amplifies the strain induced into nano-scaled sensing elements while the bulk materials are still at small strain regime, therefore enhancing the sensitivity of the sensors. For proof of concept, we utilized SiC nanowire fabricated using focused ion beam from an epitaxially grown thin film. Experimental results show significant 3-fold enhancement in the sensitivity in comparison to conventional structures, which is in good agreement with analytical modeling and numerical simulation. The proposed design shows potential for the development of miniaturized highly sensitive but robust nano mechanical-sensors.

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The current-and voltage-scaled sensitivities and signal-to-noise ratios (SNR) (with respect to thermal noise) of various octagonal AlGaN/GaN and InAlN/GaN Hall-effect sensors were examined in this work. The effect of metal contact lengths on sensitivity and sensor offset was evaluated. Calculations that take into account the shape of the device show that devices with point-like contacts have the highest current-scaled sensitivity (68.9 V/A/T), while devices with contacts of equal length to their non-contact sides have the highest voltage-scaled sensitivity (86.9 mV/V/T). The sensitivities of the two other devices follow the predicted trends closely. All the devices have offsets less than 20 µT at low supply current operation (< 300 µA) and most remain below 35 µT at higher supply current (up to 1.2 mA). The consistent low offsets across the devices imply that the choice of Hall-effect sensor geometry should mainly depend on whether the device is currentbiased or voltage-biased and the frequency at which it will operate. This work demonstrates that GaN Hall-effect sensor performance can be improved by adjusting the geometry of the Hall-effect plate specific to its function (e.g., power electronics, navigation, automotive applications).Index Terms-Hall effect, gallium nitride, AlGaN/GaN, InAlN/GaN, offset voltage, sensitivity, geometry. Engineering