Vertical hopping conduction via virtual states in intentionally disordered superlattices

A new mechanism of vertical conduction in intentionally disordered superlattices is examined. It is shown that low-temperature conduction due to phonon-assisted tunneling between distant quantum wells of a superlattice is determined mainly by hopping processes via virtual intermediate states. Under standard conditions a weak temperature dependence of vertical conduction is obtained for this mechanism. The characteristic behavior of the conductivity as a function of disorder amplitude is found for this mechanism.