Theory of potential modulation in lateral surface superlattices.

We have calculated the piezoelectric coupling between a two-dimensional electron gas and the stress field due to a lateral surface superlattice, a periodic striped gate. The stress is assumed to arise from differential contraction between the metal gate and semiconductor. The piezoelectric potential is several times larger than the deformation potential and generally gives the dominant coupling. It depends on the orientation of the device and vanishes on a (100) surface if current flows parallel to a crystallographic axis. Most devices, however, are fabricated parallel to {011} cleavage planes and in this case the piezoelectric potential is at a maximum. We also discuss different elastic models for the gate and sources of screening, which include the partlyoccupied donors in a typical GaAs-AlGaAs heterostructure. PACS numbers: 77.65.Ly, 85.30.De, 73.40.Kp, 72.20.My Typeset using REVTEX