Mobility and remote scattering in buried InGaAs quantum well channels with high-k gate oxide

The authors present results on the Hall electron mobility in buried In _0.77 Ga_0.23 As quantum well channels influenced by remote scattering due to In_0.53 Ga_0.47 As/ HfO₂ interface. When the top In_0.53 Ga_0.47 As/InAlAs barrier thickness was reduced from 50 to 0 nm, the mobility degraded from 12 000 to 1200 cm²/V s while the slope of its temperature dependency in the 77-300 K range changed from the conventional negative (∼ T^-1.2-phonon- driven mechanism) to positive (∼T). The mobility degradation is attributed primarily to remote Coulomb scattering due to the fixed charges at the semiconductor/oxide interface, as followed from the simulation results. The mobility reaches maximum at a sheet carrier density value of 2× 10 ¹² cm^-2. The data indicate that passivation of InGaAs/ HfO₂ interface with in situ grown amorphous SiO_x strongly improves mobility.