Two-dimensional system of strongly interacting electrons in silicon (100) structures
V.T. Dolgopolov a, b
a Institute of Solid State Physics, Russian Academy of Sciences, Akademika Osip'yana str. 2, Chernogolovka, Moscow Region, 142432, Russian Federation
b Editorial Board of JETP Letters, Moscow, Russian Federation
Studies of various experimental groups that explore properties of a two-dimensional electron gas in silicon semiconductor systems ((100)Si-MOSFET and (100) SiGe/Si/SiGe quantum wells) in the vicinity of the metal—insulator transition are described and critically analyzed. Results are identified that are common for all research: (i) the effective mass of electrons measured at the Fermi level in the metallic region increases with decreasing electron density and, if extrapolated, tends to diverge; (ii) the behavior of the energy-averaged mass in the metallic region is quite different in the two systems under study: in Si-MOSFETs, it also exhibits a tendency to diverge, while in the SiGe/Si/SiGe quantum wells, it saturates in the limit of low electron densities; (iii) there is a small number (depending on the sample quality) of localized electrons in the metallic phase; (iv) the properties that the electron system exhibits in the insulating phase, in the vicinity of the metal—insulator transition, are typical for amorphous media with a strong coupling between particles.