The properties of resonant transmission in triple-barrier/double-quantum-well heterostructures

To understand the nature of resonant tunneling in triple-barrier/double-quantum-well structures, we have investigated the properties of transmission probability TT of such structures with use of the transfer-matrix method. The transfer matrix of the middle barrier is calculated to analyze the amplitude decay, the phase shift, and the coupling effects that are induced between the two quantum wells. The dependencies of TT and the splitting of the resonant peaks on the middle-barrier thickness, the well width, and the symmetry of the structures are calculated. The origin of the transmission resonance and the resonant condition for symmetric (equal well widths) and asymmetric structures are discussed. The variations of TT with the applied voltage are also analyzed. The calculation results lead to some suggestions on how to design triple-barrier structures with improved performance.