Charge density and orientation dependence of the effectiveness mass in electron inversion layers on the principal surfaces of Si

Abstract

The effective mass in two dimensional space charge layers has been determined from plasmon resonance experiments on the three principal surfaces of Si for a wide range of charge densities N S =0.5×10 12cm -2 to 1.2× 10 13cm -2 and different directions of the plasmon wavevector in the surface. We report first plasmon experiments on Si (110) and verify an anisotropic plasmon mass. Special attention is paid to the low density regime where electron-electron interaction and localization effects are expected. On all surfaces we find a mass enchancement with decreasing charge density. The onset of the mass enchancement occurs at different charge densities for the different surfaces and is correlated with the Fermi energy.