Zero-field spin splitting in In_0.52Al_0.48As/In _xGa_1-xAs metamorphic high-electron-mobility-transistor structures on GaAs substrates using Shubnikov-de Haas measurements

Shubnikov-de Haas measurements were carried out for In _0.52Al_0.48As/In_xGa_1-xAs metamorphic high-electron-mobility-transistor structures grown on GaAs substrates with different indium contents and/or different Si δ-doping concentrations. Zero-field (B→0) spin splitting was found in samples with stronger conduction band bending in the InGaAs well. It was shown that the dominant spin splitting mechanism is attributed to the contribution by the Rashba term. We found that zero-field spin splitting not only occurs in the ground electron subband, but also in the first excited electron subband for a sample with Si δ-doping concentration of 6×10¹²cm^-2. We propose that this In_0.52Al_0.48As/In_xGa _1-xAs metamorphic high-electron-mobility-transistor structure grown on GaAs may be a promising candidate spin-polarized field-effect transistors.