Bipolar Magnetotransistor: Relative Sensitivity Revisited

In this paper we deduce and discuss a new analytical expression for the relative magnetic sensitivity Sr of bipolar magnetotransistors, which incorporates the ambipolar nature of the device operation in the description of the magnetic performance. Our expression accounts for the previously reported [1] trade-off between optimal electrical performance and maximum magnetic sensitivity, commonly found in bipolar magnetotransistors. Moreover, we are able to express Sr in terms of electrical parameters, such as emitter efficiency and common-emitter current gain, physical parameters, like minority carrier diffusion length or minority-carrier lifetime in the base region, and geometrical parameters, like the lateral spacing between emitter and collector.