The book contains a comprehensive review of the physics, modelling and simulation of electron transport at interfaces in semiconductor devices. Particular emphasis is put on the consistent derivation of interface or boundary conditions for semiconductor device simulation. It combines a review of existing interface charge transport models with original developments. A unified representation of charge transport at semiconductor interfaces is introduced. Models for the most important interfaces are derived, classified within the unique modelling framework, and discussed in the context of device simulation. Discretization methods for numerical solution techniques are presented.