(a) The conduction band profile and electron wavefunction in the lowest subband for a quantum well calculated using a finite-difference method (Ref. 16). is the Fermi energy. (b) The mobility as a function of carrier density in sample V256 at , both in the dark and after illumination.
The carrier density determined by Hall effect as a function of gate voltage in (a) device V256 and (b) device V266. The data from four different cool-downs are plotted. The transition to two electric subbands is shown for each device.
, , and the corresponding FFT spectrum of at gate voltages from in steps of for device V256 (cool-down 2). The magnetic field scale at each gate voltage has been normalized to the fundamental field of the SdH effect from the lowest subband so that features at the same Landau level filling factor line up.
The FFT spectrum of for device V266 (cool-down 2) as a function of gate voltage at . The peak labeled MIS at is the MIS effect for a subband spacing of . The inset shows the raw data in for on the gate.
(a) The difference in the spin-split carrier density in the lowest subband as a function of total carrier density for device V256. (b) The difference in the spin-split carrier density in the lowest subband and the second subband as a function of total carrier density for device V256. The shaded areas show the region of two subband occupation.
The Rashba coefficients in the lowest subband and the second subband for V266 at as a function of the total carrier density. The insets show the potential profile at (structural inversion symmetric) and (structural inversion asymmetric). The data points for are from the first cool-down.
A summary of the electrical properties of the wafers.
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