  Carrier generation by impact ionization and subsequent recombination under
the influence of magnetic field has been studied for InSb slab. A simple
analytic expression for threshold electric field as a function of magnetic
field is proposed. Impact ionization is suppressed by magnetic field. However,
surface recombination is dependent on the polarity of magnetic field:
strengthened in one direction and suppressed on the opposite direction. The
former contributes quadratic increase to threshold electric field, and the
latter gives additional linear dependence on magnetic field. Based on this
study, electrical switching devices driven by magnetic field can be designed.
