the structure of fig1 a is shown barrier layers 13 and 14 are shown to have a wider bandgap 23 and 25 respectively than the bandgap 24 of well 14 the band edge offset for the conduction band is shown as 20 and the band edge offset for the valence band is shown as 21 according to the invention for the first time polycrystalline material may be employed as a layer in a quantum well or superlattice this provides the advantage of less expensive fabrication and higher yields even more importantly it opens up a whole new range of well characterizedmaterials to be used in the quantum well or superlattices quantum wells and superlattices are freed from lattice matching constraints required of multiple epitaxial layer structures the passivated polycrystalline layer 14 may be fabricated of polycrystalline silicon germanium or group iii v compounds general considerations will first be described examples of thefabrication of each will then be described in order to passivate a grain boundary of a polycrystalline material more than one element may be employed this is so due to the three dimensional topology and the various types of dangling bonds resulting therefrom in general amorphous materials 29 such as amorphous silicon dioxide for polycrystalline silicon and amorphous germanium oxide for polycrystalline germanium can facilitate the formation of bonds on neighboring grains these amorphous materials 29 facilitate this process by chemically reacting with the polycrystalline material to satisfy dangling bonds on the grains 28 which previously acted as electron traps as seen in fig1 d an important consideration in.