Rashba spin splitting in inversion layers onp-type bulk InAs

The dependence of the spin-orbit interaction on electron density in inversion layers of metal-oxide-semiconductor field-effect transistors on p-type InAs is studied by magnetotransport at liquid-helium temperatures. We observe beating patterns in the Shubnikov--de Haas oscillations, which manifest the Rashba effect in a triangular surface potential. Taking subband nonparabolicity into account we evaluate Rashba parameters α that increase with electron density nₛ reaching a value α=3×10^-11eVm at densities nₛ>~2.2×10¹²cm^-2. Implications for the spin-dependent transport in spin-polarized high-electron-mobility transistors utilizing InAs quantum wells are discussed.