Exchange and correlation effects on screening in two-dimensional electron gas.

A simple expression for the screening constant in a two-dimensional electron gas (2DEG) of finite thickness is obtained within the framework of a 2D version of the linearized Thomas-Fermi- Dirac equation, which includes effects of the exchange-correlation energy. For the case of 2DEG in an AlGaAs/GaAs system the role of the correlation energy is shown to be small compared to that of exchange. Effect of the exchange energy on the screening constant decreases with the increasing surface concentration n of electrons. For n ~ 10 sup (11) cm sup (-2) the screening constant increases by 50% compared to its value calculated for noninteracting particles. The calculated value of the impurity- scattering limited mobility is shown to increase by an approximately similar factor.