M. Streibl et al., Imaging of acoustic charge transport in semiconductor heterostructures by surface acoustic waves, APPL PHYS L, 75(26), 1999, pp. 4139-4141
We demonstrate room-temperature acoustic charge transport of electrons and
holes in an InGaAs/GaAs heterostructure. The carriers are optically generat
ed by interband absorption and then separated, stored, and transported in t
he piezoelectric potential superlattice of a surface acoustic wave. The cha
rge distribution is detected with a spatial resolution of a few acoustic wa
velengths by a second orthogonal probe beam, genererated by so-called taper
ed transducers. The image information is given as a phase shift signal in f
requency space and allows for the direct comparison of the number of genera
ted and transported carriers. Regions of mere carrier drag and full carrier
capture and transport are observed simultaneously. (C) 1999 American Insti
tute of Physics. [S0003-6951(99)01252-8].