Mobility of the non-polarized and the spin-polarized electron gas in Si/SiGe heterostructures: Remote impurities
Centre d'Elaboration de Materiaux et d'Etudes Structurales (CNRS) - 29 Rue Jeanne Marvig, 31055 Toulouse, France, EU
2 UFR-PCA, Université Paul Sabatier - 118 Route de Narbonne, 31062 Toulouse, France, EU
Accepted: 27 November 2010
We analyze low-temperature ultra-high–mobility data (μ ≤ 1.6×106 cm2 /Vs) obtained for the two-dimensional electron gas in Si/SiGe heterostructures with Al2O3 as the gate oxide. We find that charged impurities of density Nid = 5.5×1012 cm−2, located at the SiGe/Al2O3 interface at a distance d = 1500 Å from the electron gas, are important for the mobility. A metal-insulator transition is predicted at low electron density (near 2×1010 cm−2). We discuss the importance of many-body effects (exchange and correlation) for the mobility for the non-polarized and the spin-polarized electron gases. Suggestions are made to increase the mobility in such structures.
PACS: 73.20.Fz – Weak or Anderson localization / 73.50.Bk – General theory, scattering mechanisms / 73.40.Qv – Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
© EPLA, 2010