Monte Carlo study of apparent magnetoresistance mobility in nanometer scale metal oxide semiconductor field effect transistors

This paper investigates the mobility extraction from channel magnetoresistance, which is widespreading as a powerful experimental method to study transport in short gate devices. A fully self-consistent Monte Carlo device simulator is used to simulate the influence of a transverse magnetic field on electron transport in nanometer scale devices. After validation on a simple silicon magnetic sensor, the method is applied to the simulation of the channel magnetoresistance of nanoscale double gate metal oxide semiconductor field effect transistors. Apparent magnetoresistance mobilities μMR are extracted from channel resistance variation with the applied magnetic field, using a measurement-inspired extraction method. The simulated temperature trends obtained by simulation are consistent with experimental data. As experimentally observed elsewhere, the extracted apparent mobility decreases with the shrinking of the channel length. No additional scattering mechanism specific to short channel devices was needed to observe this effect. This apparent mobility reduction observed in the simulated results is shown to originate from nonstationary transport, which is discussed and interpreted using simple numerical calculations. We propose a Mathiessen-like formalism in order to quantify this effect. Finally, ballistic transport is shown to have a significant impact on the apparent mobility extraction and must be taken into account if the apparent magnetoresistance mobility is to be used as a figure of merit to assess short device performance.