High magnetoresistance in bipolar semiconductors by impurity concentration optimisation

The well known two carrier transverse magnetoresistance in semiconductors is analysed in order to show that a high magnetoresistance coefficient can be reached for an impurity concentration which closely depends on the electron-hole mobility ratio and the magnetic field intensity. The condition for a strong magnetoresistance is shown to be quite different from that leading to a null Hall field. Experiments in InSb crystals fully confirm the analysis and outline the possibility to use this effect for magnetic or temperature sensors.