Determination of spin- and valley-split energy levels in strained Si quantum wells

The energy spacing of spin- and valley-split energy levels in strained Si quantum wells is determined using tilted-magnetic-field Shubnikov - de Haas measurements. The effective Landé g-factor, , is determined both as a function of electron sheet concentration, , and Landau level occupation number, . The value of is determined from the angle at which the longitudinal magnetoresistance minima of adjacent spin-split Landau levels are equal. For the coincidence of the and levels, increases from to as is decreased from to at T = 0.4 K. In the same sample, with fixed electron concentration of , for , and oscillates between average values of and , for lower values of . The magnitude of the valley splittings has also been investigated; for a perpendicular magnetic field of , a splitting of is determined, which is several times smaller than values for Si inversion layers reported in the literature.