DIFFUSION THERMOPOWER OF A SILICON INVERSION LAYER AT LOW MAGNETIC-FIELDS

We have investigated the longitudinal and transverse thermopowers, S-x x and S-yx, of an electron inversion layer in a Si-metal-oxide-semicon ductor field-effect transistor at low magnetic fields in the temperatu re range similar to 0.5-4 K. We show that a single theoretical model, based on the Mott relation for diffusion, gives a good account of both the quantum oscillations and the smooth background at low temperature s where phonon drag can be ignored. An anomalous nonoscillatory compon ent, possibly due to phonon drag, is found in S-yx at higher temperatu res.