Materials Used in Hall Devices
The characteristics of Hall devices are determined by their material and shape, and vary according to two material constants:
Electron mobility μ
Energy band gap Eg
The larger the electron mobility μ is, the higher the sensitivity becomes. The larger the energy band gap Eg is, the better the temperature characteristics of the Hall device are. Values for μ and Eg for the main materials used are shown in Table 1 below.
Estimated values of Electron mobility and energy band gap for different materials
The characteristics of Hall devices made with each of the above materials are as follows:
Although temperature characteristics are good, sensitivity is low and imbalance voltage VHO (voltage generated without application of a magnetic field) is large. Presently, silicon Hall devices are used mainly as Si Hall ICs with an amplifier or other devices integrated on a single chip, rather than as simple Hall devices.
This material features high sensitivity due to high electron mobility, but the small band gap causes considerable temperature drift.
With less electron mobility than InSb, this material has lower sensitivity, but because the band gap is greater than that of InSb, temperature drift is smaller. This material is used in Hall probes for measuring magnetic fields due to its good linearity with respect to magnetic fields.
GaAs's large band gap produces a low temperature drift. While its electron mobility is smaller than that of InSb, lowering its sensitivity.
Two-dimensional electron-gas (2-DEG) Hall elements developed and produced by AHS Ltd using MBE have high sensitivity and stability over a wide temperature range and have potential for present and future applications required by many electronic systems.