ELECTRON-WAVE FILTERS FROM INVERSE SCATTERING-THEORY

Semiconductor heterostructures with prescribed energy dependence of th e transmittance can be designed by combining: a) Pade approximant reco nstruction of the S-matrix; b) inverse scattering theory for Schroding er's equation; c) a unitary transformation which takes into account th e variable mass effects. The resultant continuous concentration profil e can be digitized into an easily realizable rectangular-wells structu re. For illustration, we give the specifications of a 2 narrow band-pa ss 12-layer AlcGa1-cAs filter with the high-energy peak more than twic e narrower than the low-energy one.