Temperature dependence of the diffusive thermopower in the two-dimensional interacting electron gas

We evaluate the thermoelectric properties of the interacting two-dimensional electron gas in the presence of disorder at low temperatures. The diffusive (d) thermoelectric power (Seebeck coefficient) Sd (T) as function of the temperature T is calculated using the relaxation time approximation and we find Sd(T→0)/T=c1+c2T if short-range disorder is considered. The anomalous screening properties of the two-dimensional electron gas due to the Kohn anomaly, also responsible for Friedel oscillations, lead i) to a new contribution to c1 depending on interaction effects and ii) to an anomalous temperature dependence $c_2 \ne 0$ of the thermopower. It is shown that at low density many-body effects due to exchange and correlation strongly modify the thermopower. Numerical results for Si-MOSFET structures are presented.