Quasiballistic transport in nanometer Si metal-oxide-semiconductor field-effect transistors: Experimental and Monte Carlo analysis

Abstract

Room temperature electron mobility (μ) in nanometer Si metal-oxide-semiconductor field-effect transistors (MOSFETs) with gate length (LG) down to 30 nm was determined by the magnetoresistance method. A decrease of μ with the decrease of LG was observed. Monte Carlo simulations of electron transport in nanometer MOSFETs were carried out for realistic devices as a function of LG. The dependence with LG and electron concentration of simulated mobility and transmission coefficient agree with experimental data. An analysis of scattering events and time of flight gives evidence of the presence of ballistic motion in the investigated structures and proves its influence on mobility degradation in short transistors. The results give arguments that interpretation of the magnetoresistance coefficient as the square of the mobility is valid also in the case of quasiballistic electron transport.

Onset of quasi‐ballistic transport and mobility degradation in ultra scaled MOSFETs: a Monte Carlo study

“…When the gate length is reduced, a slight reduction in the values of µ is initially observed; however, when the devices are scaled below 50 nm L g , an important drop in the mobility values takes place. This result is in good qualitative agreement with the experimental data reported in [2,12], thus confirming an overall degradation of the channel mobility as devices are scaled into the nanometre range.…”

Monte Carlo simulation of graded-channel fully depleted SOI nMOSFETs

“…For this calculation, a counting region is considered [11] limited by two surfaces. In this case this region corresponds to the entire channel of the devices, with the entering surface at the source-channel junction and the exiting surface at the channeldrain junction.…”

“…The analysis of several internal quantities provided by the MC simulation also offers interesting information. The longitudinal profiles are obtained from the 2D results weighted by the local concentration in the vertical (Y) direction [11]. In Fig.…”

“…Numerical simulations have been performed by means of our in-house ensemble two-dimensional Monte Carlo bipolar simulator. The simulator has been successfully employed for the study of the static, dynamic and noise properties of several MOS devices [8][9][10][11]. The characteristics of the scattering mechanisms included in the Monte Carlo simulator, the conduction and valence band structures of Silicon and the parameters considered for electrons and holes can be found in [8,9] and references therein.…”

Scale-Invariant Drain Current in Nano-FETs

“…Naturally, these approaches rely to an essential extend on numerical methods. Therefore in many cases the scaling properties of nanotransistors have been extracted from simulations of concrete systems with given physical sizes [41,42,43,44,45]. As a complementary approach, there is a number of simpler one-dimensional effective models which lead to a more compact description (for a review see Ref.…”