Charge-carrier exclusion and accumulation intensified by ohmic contacts

Abstract

The effect of the high generation-recombination power of an ohmic contact (S contact) on exclusion-accumulation processes in structures with an antiblocking contact (asymmetric structures of the type p+-p-S) was studied theoretically and experimentally. It is shown that, in contrast to the ordinarily studied symmetric structure p+-p-p+, the asymmetric structures, which is being studied, forms a region of accumulation or exclusion, depending on the direction of the current. The nonequilibrium carrier density in the accumulation layer is much higher while the exclusion region is longer than in the symmetric structure. A density n 100 times higher than the equilibrium value n0 was obtained experimentally for Ge at 300 K. The length of the exclusion region reached 96% of the sample length. Applications of structures with antiblocking and ohmic contacts based on narrow-gap materials are proposed.