Breakdown Voltage using Ionization Integrals : Breakdown Voltage using Ionization Integrals

Requires: SSuprem 4/S-Pisces
Minimum Versions: Athena 5.22.3.R, Atlas 5.24.1.R

This examples uses a standard NMOS structure similar to that used in the MOS1 section. In this example the Atlas simulation is performed using zero carriers . The breakdown voltage is extracted using ionization integrals or electric field lines

The solve statement used to ramp the drain electrode has extra parameters for calculating the ionization integrals at each step. When using ionization integrals it is not necessary to solve for both carriers so simulations are very fast. However, the statement impact selb must be used to activate the ionization rate calculation.

The syntax of the solve statement sets the number of ionization integrals, their position relative to the ramped contact (ie. drain), and the voltage drop from the contact to the start point of the electric field lines. Details of the syntax can be found in the Atlas User Manual. deltav controls the distance of the start of each electric field line from the ramped contact. ionlines controls the number of electric field lines calculated. lratio controls the spacing ratio between each line. Lratio < 1.0 means more lines to the left of the contact. Lratio > 1.0 means more lines to the right.

The breakdown voltage is defined as the point at which the ionization integrals are equal to 1.0. Although the solve statement specifies a voltage ramp to 50V, the bias ramp will automatically stop when the ionization integrals exceed 1.0. The parameter ^ionstop can be included to disable this feature. If the position of the electric field lines are chosen correctly the electron and hole ionization integrals should equal 1.0 at the same voltage. If this is not the case, users should check the position of the electric field lines.

The output statement is used to specify the electric field line parameters for the saved solution file. Note that users must specify these parameters on the output as well as solve statements to save the electric field lines. The lines can be plotted in Tonyplot by selecting the LINES icon from the PLOT/DISPLAY menu.

Following the simulation, the peak electric field is extracted from the solution file. The extract statement also reports the XY position of the peak. See the Simulation Standard Hints and Tips page for August 1996 for more details.

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.