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 In0.77Ga0.23As quantum well channels influenced by remote scattering due to In0.53Ga0.47As/HfO2 interface. When the top In0.53Ga0.47As/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 2×1012 cm−2. The data indicate that passivation of InGaAs/HfO2 interface with in situ grown amorphous SiOx strongly improves mobility.