Tunneling spectroscopic study of finite superlattices

We present a tunneling density of states study of the transition from a superlattice miniband to a sequential coupled well structure. We have observed by tunneling spectroscopy the eigenstates of a finite superlattice system far below the Stark localization threshold. The transition from an indistinguishable miniband to a coupled well structure is experimentally found to be 2.5 meV ≤W(miniband width)/n(♯ periods) ≤10.5 meV.