Sequential resonant tunneling of holes in GaAs-AlAs superlattices

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Abstract
We have studied carrier transport in an electric field perpendicular to the layers of GaAs-AlAs superlattices. We observed structures in the field dependence of the transport characteristics which are attributed to sequential-resonant-tunneling processes between hole subbands. This interpretation is strongly supported by the energy splitting between the valence subbands determined from photocurrent spectra. In addition, there is some experimental evidence that these transport processes take place not only between different heavy-hole subbands but also from heavy-hole subbands into light-hole subbands. The occurrence of the latter transport process is a direct consequence of the coupling between the light- and heavy-hole subbands at finite parallel momentum due to nonparabolicities.