4.3.2 Magnetic Field

Figure 4.83 shows the differential current as a function of the magnetic field at 77 K and 300 K. The simulation results perfectly match the experimental data at 77 K. In this case the Hall scattering factor for electrons has been set to 0.8. From the data in Figure 3.1 [18], the Hall scattering factor increases as the temperature decreases. Although the absolute values of the Hall scattering factors for electrons used in the simulations do not agree with the values found in [18], the increase of the Hall scattering factor for electrons from 0.6 at 300 K to 0.8 at 77 K in this thesis seems to be reasonable in view of the match of the simulation results with the experimental data. The bias of the two-drain MAGFET are a gate voltage of 4.95 V, a drain voltage of 1.0 V in both drains, and zero volts in the source and substrate.

Figure 4.83: Differential current versus magnetic field at 77 K and 300 K.

At 77 K the relative sensitivity is 11.09 % T$^{-1}$ according to (4.1). This value is notably higher compared to the room temperature value and even to other solid-state sensors. The improvement in the relative sensitivity is due to the increase in the electron mobility in the inversion layer. As it has been stated in (4.2), the higher the carrier mobility, the higher the carrier deflection. As a result, the differential current increases, as can be seen from Figure 4.83 where the 300 K case has been plot for a quick comparison.