Abstract
For pt.I see ibid., vol.20, no.13, p.1985 (1987). A general formula for the phonon-drag contribution to the thermopower of quasi-2D electrons coupled to 3D phonons is evaluated for low temperatures when the electrons are in the electric quantum limit and the phonons are in the boundary scattering regime. The formula is most simply applied to GaAs/AlGaAs heterojunctions. An extension of the theory is required before it can be applied to Si MOSFETs due to the anisotropic nature of Si. In both cases good agreement is found between theoretical predictions and recent experimental results.