Non-local inelastic trap assisted tunnelling in a MOS-C

quantumex20.in : Non-local inelastic trap assisted tunnelling in a MOS-C

Requires: S-Pisces
Minimum Versions: Atlas 5.28.1.R

This example shows how to model the tunneling current through an insulator defect level using the ITAT.SC.EL model.

It demonstrates :

  • Setting up a Trap level for tunnelling using the DOPING statement
  • Setting up a self-consistent version of the ITAT model.
  • Visualising the results of the ITAT model.

A simple MOS-C is set up using Atlas mesh commands, and the statement
doping region=2 uniform tat.trap conc=1.0e19 acceptor sign=1.0e-13 sigp=1.0e-13 e.level=3.0
sets up a spatially uniform trap concentration with the tat.trap parameter. These traps are unlike conventional traps and their occupancy fractions are determined solely by the tunnel current passing through them. This statement also sets the trap capture cross sections (1.0e-13 cm^2), type (acceptor) and energy level below the conduction band (3.0 eV). The ITAT.SC model for electrons is enabled on the models statement
models itat.sc.el tat.slicepts=51
This causes a quantum tunnelling region to be automatically set up, with 51 points along each tunnelling slice. The self-consistency means that the tunnel current is injected into the current continuity equations in the semiconductor.

The next part is a steady state voltage ramp of the gate. This causes a tunnel current to flow through the traps in the oxide, and affects their occupation probabilities by charging them up. After this the gate voltage is returned to zero on a transient ramp and the current obtained up to a simulation time of 0.01 s. After the initial transients, the tunnelling current decays with a power law dependence on time. The change of charge in the device causes a displacement current to be present too. The trap occupancy is shown as a function of depth in the oxide for the equilibrium case, when the steady-state bias is 2.0V and after partially discharging.

To load and run this example, select the Load button in DeckBuild > Examples. This will copy the input file and any support files to your current working directory. Select the Run button in DeckBuild to execute the example.