Inversion layer electron mobility distribution in fully-depleted silicon-on-insulator MOSFETs

Magnetic-field dependent geometrical magnetoresistance measurements and high-resolution mobility spectrum analysis have been employed to characterise the inversion-layer electron mobility distribution in fully-depleted silicon-on-insulator MOS transistors. The results reveal that the room-temperature electron population in the 12 nm thick Si channel layer is characterised by a broad electron mobility distribution that significantly departs from the ideal single-value discrete carrier approximation. At temperatures below 60 K, the linewidth of the distribution is shown to become significantly narrower, approaching a delta-like function at 30 K. Self-consistent Schrödinger-Poisson numerical calculations suggest that, since the total carrier population at 295 K is comprised of electrons in the ground-state level of the two subband ladders, intervalley scattering and phonon scattering will significantly influence the linewidth of the mobility distribution in the transistor channel. To the best of our knowledge, electron mobility distributions in Si-based devices have not been previously studied nor resolved in such detail.