A TiOx/AlOx resistance switching device was investigated as a prototype of a bilayered structure composed of a "transport layer" and a "tunnel layer." Study of its carrier transport led to the conclusion that resistance switching is driven by the modulation of the AlOx tunnel barrier. Redox in the AlOx layer causes the decrease in tunneling resistance that scales with the inverse of the area. The appropriate switching characteristics in a bilayered structure can be obtained by adopting a tunnel layer that has a higher lattice binding energy than the transport layer. (C) 2010 American Institute of Physics. [doi:10.1063/1.3481076]