Field effect two-dimensional electron gases in modulation-doped InSb surface quantum wells

We report on transport characteristics of field effect two-dimensional electron gases (2DEGs) in surface indium antimonide quantum wells. The topmost 5 nm of the 30 nm wide quantum well is doped and shown to promote the formation of reliable, low resistance Ohmic contacts to surface InSb 2DEGs. High quality single-subband magnetotransport with clear quantized integer quantum Hall plateaus is observed to filling factor nu = 1 in magnetic fields of up to B = 18 T. We show that the electron density is gate-tunable, reproducible, and stable from pinch-off to 4 x 10(11) cm(-2), and peak mobilities exceed 24 000 cm(2)/Vs. Large Rashba spin-orbit coefficients up to 110meV . angstrom are obtained through weak anti-localization measurements. An effective mass of 0.019m(e) is determined from temperature-dependent magnetoresistance measurements, and a g-factor of 41 at a density of 3.6 x 10(11) cm(-2) is obtained from coincidence measurements in tilted magnetic fields. By comparing two heterostructures with and without a delta-doped layer beneath the quantum well, we find that the carrier density is stable with time when doping in the ternary Al0.1In0.9Sb barrier is not present. Finally, the effect of modulation doping on structural asymmetry between the two heterostructures is characterized.