alternative the quantum wave interference layer can be made of group iii v compound semiconductor group ii vi compound semiconductors si and ge and semiconductors of other hetero material the desirable compositions are as follows each combinations is represented by a composition of a layer having a wide band width a layer having a narrow band width a substrate and x and y are arbitrary values wherein 0 u2266 x u2266 1 and 0 u2266 y u2266 1 as long as they are not specified lt 1 gt al x in 1 x p ga y in 1 y p gaas lt 5 gt alas al x ga 1 x as gaas 0 8 u2266 x u2266 0 9 lt 6 gt inp ga x in 1 x as y p 1 y gaas lt 8 gt si sige x c y arbitrary material 0 1 u2266 x u2266 0 3 0 u2266 y u2266 0 1 lt 9 gt al x1 ga y1 in 1 x1 y1 n al x2 ga y2 in 1 x2 y2 n si sic gan or sapphire 0 u2266 x 1 x 2 y 1 y 2 x 1 y 1 x 2 y 2 u2266 1 while the invention has been described in connection with what are presently considered to be the most practical and preferred embodiments it is to be understood that the invention is not to be limited to the disclosed embodiments but on the contrary the description is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims the present document claims the benefit of japanese priority document filed in japan on dec 17 1998 the.