Daniel Bessis, Giorgio Mantica, G. Andrei Mezincescu, and Daniel Vrinceanu
Electron Wave Filters from Inverse Scattering Theory
(56K, postscript file (4 pages))

ABSTRACT.  Semiconductor heterostructures with prescribed energy dependence of
the transmittance can be designed by combining: {\em a)} Pad\'e 
approximant reconstruction of the S-matrix; {\em b)} inverse scattering 
theory for Schro\"dinger's equation; {\em c)} a unitary transformation 
which takes into account the variable mass effects. The resultant continuous 
concentration profile can be digitized into an easily realizable 
rectangular-wells structure. For illustration, we give the specifications 
of a 2 narrow band-pass 12 layer $Al_cGa_{1-c}As$ filter with the high 
energy peak more than {\em twice narrower} than the other.