Electron mobility in heavily doped junctionless nanowire SOI MOSFETs

•Mobility in highly doped junctionless trigate MOSFETs is experimentally studied.•Mobility enhancement in narrow nanowire versus wide devices is demonstrated.•Mobility values in narrow nanowire MOSFETs exceed the bulk mobility value.•These effects are due to reduced impurity scattering in narrow nanowire devices. This paper presents experimental results on the effective electron mobility in heavily doped tri-gate nanowire junctionless SOI MOSFETs with various nanowire widths. Significant enhancement of the electron mobility in narrow nanowire devices, as compared to counterpart planar (wide) devices, having the same film thickness and doping, and as compared to the bulk silicon mobility with the same doping is demonstrated. This effect is attributed to the reduced impurity scattering in narrow nanowire devices. The obtained results are seen to be very important as low carrier mobility due to high doping was previously assumed to be the fundamental limitation of junctionless nanowire devices.