The electrical susceptibility of the Silicon-electrolyte interface has been studied when the electrical irradiation field is parallel to the junction. In the High Frequency (H.F.) range, the absorption exhibits one maximum depending on the voltage applied between the semi-conductor and the electrolyte. This drastic variation, specially the maximum, is at our opinion, due to the minority carriers. It is modified by irradiation. In the microwave range, the maximum of absorption is rather difficult to observe probably because electrochemical reactions occur. The variation of dispersion is negative, we explain that by considering the high frequency local field.

The resonances a t microwave frequencies can be observed in polarized junctions ; this was studied in previous papers and we have called for an important contribution of minority carriers. With a magnetic field B, a non diagonal component of the electrical conductivity can exist, a sort of microwave Hall effect. This can be considered as the effect of the non-diagonal part of the microwave susceptibility along the E A B direction. We report the observation of this non-diagonal component, which allows to verify the sign of the charge carriers. This experiment can be considered as a generalization of the d.c. Hall effect.

The spin of the electrons has an incidence on the electrical transport properties, especially on the recombination of charge carriers. The minority carriers are usually considered t o have a negligible effect on the behaviour of semiconductor-metal junctions. We describe an experience which shows, that their role is evident. The experience consists in studying the efficiency of a junction while producing E.S.R., which modifies the recombination rate of minority carriers.