An energy band-pass filter using superlattice structures

A novel quantum mechanical energy band-pass filter (EBPF) using semiconductor superlattices is proposed. Such structures with a Gaussian superlattice potential profile allow the incident electrons to be nearly totally transmitted when the impinging electron energy is in the passband. On the other hand, a complete reflection occurs when the impinging energy is in the stopband. By adjusting the parameters of the potential profile and the superlattice, the desired passband and stopband of such filter can be obtained. Time evolution of an electron wave packet moving through such a structure is calculated by numerically solving the time-dependent Schrodinger equation. The numerical simulation clearly demonstrates the characteristics of total transmission and total reflection. The generalized concept of matched quantum-mechanical wave impedance (QMWI) analogous to that used in the transmission line theory is presented to explain the occurrence of total transmission of the proposed structures