On the ballistic transport in nanometer-scaled double-gate MOSFET

TL;DR

This paper investigates ballistic transport in nanometer-scale double-gate MOSFETs using Monte Carlo simulations, revealing that the drive current approaches the ballistic limit even with non-ballistic electrons and highlighting the importance of the entire channel length in ultra-short devices.

Contribution

It provides a detailed analysis of scattering effects and transport characteristics in 15 nm and shorter channels, emphasizing the role of the entire channel in determining drive current.

Findings

Most back-scattering occurs in the first half of the channel.

Drive current in 15 nm channels is close to the ballistic limit.

Second half of the channel remains significant in ultra-short transistors.

Abstract

The scattering effects are studied in nanometer-scaled double-gate MOSFET, using Monte Carlo simulation. The non-equilibrium transport in the channel is analyzed with the help of the spectroscopy of the number of scatterings experienced by electrons. We show that the number of ballistic electrons at the drain end, even in terms of flux, is not the only relevant characteristic of ballistic transport. Then the drive current in the 15 nm-long channel transistor generations should be very close to the value obtained in the ballistic limit even if all electrons are not ballistic. Additionally, most back-scattering events which deteriorates the ON current, take place in the first half of the channel and in particular in the first low field region. However, the contribution of the second half of the channel can not be considered as negligible in any studied case i.e. for a channel length below 25 nm. Furthermore, the contribution of the second half of the channel tends to be more important as the channel length is reduced. So, in ultra short channel transistors, it becomes very difficult to extract a region of the channel which itself determine the drive current Ion.