Vertical hopping transport in doped intentionally disordered superlattices

We discuss electronic states and vertical transport in doped superlattices with intentional vertical disorder introduced by controlled random variations of well widths. For structures with sufficiently large disorder, the vertical conductance is due to hopping between the wells and can be described by the rate equation for inter-well transitions. At low bias, the rate equation is reduced to the equivalent resistance network. This network is generally different from the Miller-Abrahams network and contains multisite resistors. A percolative approach to the calculation of the total network resistance is considered. It is argued that for second-nearest neighbor hopping involving intermediate-well virtual states, the vertical conductance of the structure can exhibit weakly activated or nonactivated quasimetallic behavior.