AC FIELD-ASSISTED CURRENT IN GAAS-ALGAAS SUPERLATTICES

The application of an external time dependent potential to a superlatt ice modifies its transport properties. We have analyzed theoretically the photoassisted tunneling current through a superlattice in the pres ence of an a.c. potential applied at both sides of the superlattice. I n the presence of a finite d.c. bias, the miniband structure for the c onduction band of the superlattice becomes the well known Stark ladder and the tunneling current takes place sequentially. The a.c, field in duces absorption and emission processes which are reflected as new fea tures in the current density. These new features in the tunneling curr ent are due to new effective tunneling channels coming from the photos ide bands which are opened, and which produce additional current steps in the characteristic curve. Our theoretical results are in good agre ement with the available experimental evidence.