Transition between N- and Z-shaped current-voltage characteristics in semiconductor multiple-quantum-well structures

The vertical electron transport in semiconductor multiple-quantum-well structures within the sequential tunneling approaches and under assumption of resonant interwell transitions is analyzed. A transition between N- and Z-shaped curves is observed when the number of layers in the structure is varied and the structures with sharp transition resonances and low overall conductivity are in favor of the formation of Z-shaped portions of I-V curves.