Electronic transmission in random trimer InAs/InxGa1−xAs superlattices

We study theoretically the effects of short-range correlated disorder and applied bias on the nature of the transport properties in InAs/InxGa1−xAs superlattices. We consider layers having identical thickness where the (In) concentration x takes at random two different values with the additional constraint that barriers (wells) of one kind always appear in triple, thus forming random trimer barrier superlattices (RTBSL). We have numerically examined with the use of the exact Airy function formalism and the transfer-matrix method, the transmission properties across RTBSL. In the case of unbiased systems, we observed that the introduction of correlated disorder prevents the localization and causes delocalization states. This behavior is due to the trimer tunneling state originated for the basic cells of three singular barriers. In the case of biased systems, we see the decrease of the miniband width (reduction of transmission) until the complete disappearance for high values of Va.