Piezoelectric field effects on sensitivity of Hall sensors based on AlGaAs/InGaAs/GaAs heterostructures

The sensitivity and performance of Hall sensors depends on the electron mobility of its substrate. With the aim to design a substrate capable of operating at high-absolute magnetic sensitivity and high current-related sensitivity we investigated the theoretical consequences of utilizing a high-index GaAs substrate in AlGaAs/InGaAs/GaAs heterostructures. The shape of the confining potential, the sub-band energies, the eigen envelope wave functions, and the Fermi energy in the InGaAs channel were calculated self-consistently at low temperature, taking into account exchange-correlation, strain, and piezoelectric effects. The piezoelectric field significantly increased the electron density (n(s)) in the channel when the structure was grown on a GaAs (111)A substrate. This implies that one can have a wider spacer layer without altering n(s), with the result of enhanced electron mobility. These data suggest that AlGaAs/InGaAs/GaAs heterostructures have high electron mobility and low sheet electron density, and are suitable for a highly-sensitive Hall sensor.