1. An apparatus including a memristor, the memristor comprising: a high-conductivity layer; a diffusion barrier layer; a first layer and a second layer defining an Ohmic contact layer, the Ohmic contact layer separated from the high-conductivity layer by the diffusion barrier layer; and an active material layer forming an Ohmic contact region with the Ohmic contact layer, the active material layer including a profile of mobile dopants that is reconfigurable in accordance with programming voltages applied to the memristor.