Acoustoelectric effect in semiconductor superlattice

Acoustoelectric effect in semiconductor superlattice has been studied for acoustic wave whose wavelength δ = 2π/q is smaller than the mean free path of the electrons l (where ql >> 1). Unlike the homogeneous bulk material where Weinreich relation is independent of the wave number q in the superlattice we observe a dependence on q i.e. spatial dispersion. In the presence of applied constant field E a threshold value was obtained where the acoustoelectric current changes direction. (author). 13 refs