High temperature Hall effect sensors based on AlGaN∕GaN heterojunctions

Abstract

We report on AlGaN∕GaN heterojunction structures for use in Hall effect sensors working over a wide range of temperatures. Room temperature current-related magnetic sensitivity of 55V∕AT at a sheet resistance below 300Ω∕sq and very low temperature cross sensitivity of 103ppm∕°C up to 300°C were obtained for a square-shaped Hall effect sensor. The active layer of the Hall effect sensor is the two-dimensional electron gas formed at the Al0.3Ga0.7N and GaN heterointerface caused by the gradient in the total polarization between the AlGaN barrier and the GaN buffer layer, which results in the positive polarization induced interface charge attracting free electrons. The temperature-dependent transport properties of the heterojunction were analyzed by Hall measurement. The drop of its electron mobility from room temperature to 300°C is mainly due to the enhanced polar optical scattering, while the very stable sheet carrier density contributes to the excellent temperature cross sensitivity of the Hall effect sensor.

Batch-fabricated high-performance graphene Hall elements

“…4f). In particular, the temperature coefficient is as low as 30 ppm·K −1 below 200 K, which is much better than that of all published conventional Hall elements with typical temperature coefficient of around 1000 ppm·K −1 4262728. On the other hand, the offset voltage is also found to hardly change over a wide temperature range from 1.8 K to 400 K, which fluctuates between −4 mV and −5 mV (see Fig.…”

“…The sensitivity is seen to increase, from 494 V/AT at 1.8 K, with increasing temperature and peak at about 580 V/AT at 350 K, and then decreases with temperature. The temperature coefficient of the sensitivity is defined as262728 where S denotes either the absolute sensitivity or the current/voltage-related sensitivity. The temperature coefficient γ T of the GHE operating in current mode remains below 800 ppm·K −1 over a wide temperature range from 1.8 K to 400 K (Fig.…”

“…Excellent thermal stability over a wide temperature range from 1.8 K to 400 K is crucial for many applications of high performance Hall elements in such fields as aircraft, spacecraft, military, oil and gas industries1232628. In a conventional semiconductor, carrier density and mobility are both temperature sensitive and the thermal stability of the corresponding Hall element is generally poor262728.…”

Robust Hall Effect Magnetic Field Sensors for Operation at High Temperatures and in Harsh Radiation Environments

“…Wide bandgap of GaN shows potential for stable operation at high temperatures [1]- [4]. Furthermore, GaN and related materials are expected to have a high tolerance for high-energy particle irradiation because of their chemical stability.…”

Oriented attachment of nanoparticles to form micrometer-sized nanosheets/nanobelts by topotactic reaction on rigid/flexible substrates with improved electronic properties

“…40,41 From Figures 7a and b, the Hall voltage sensitivity, ΔV H (T, H)/V H (T, 0), Oriented attachment of nanoparticles H Qian et al of the obtained film to magnetic field H is enhanced up to 188% at room temperature, demonstrating a potential Hall effect sensor application. 42 The Hall resistance varies linearly with the magnetic flux density with a correlation coefficient R of 0.99989. The Hall coefficient R H is calculated to be − 2.38 × 10 − 4 m 3 C − 1 when the film thickness d is 7 μm.…”