The influence of external electric field on acoustoelectric effect in a superlattice

The dc acoustoelectric current jac induced by the interaction of acoustic phonons with the conducting electrons is calculated. The calculation is done in the hypersound regime where qℓ≫1 (here q is the acoustic phonon number and ℓ is the electron mean free path). The electric field consists of dc field E0 and a low frequency alternating field E1. A nonlinear dependence of jac on E0 and E1 is observed. Depending on the direction of the dc field E0 the acoustoelectric current can either be positive or negative. At ωq=1011s−1 and in the absence of E0, Jac is very small and tends to zero at E1=1.3×105Vm−1. Further increase of ωq from 1011 s−1 sees a dramatic shoot “up” of Jac. Lastly the acoustoelectric currrent in the presence of E0 is modulated by E1.