Si/SiGe HBT Gummel Plot Simulation : Si/SiGe HBT Gummel Plot Simulation

Requires: Blaze
Minimum Versions: Atlas 5.24.1.R

This example demonstrates the simulation of a SiGe HBT to extract Ic and Ib versus Vbe and plots the bipolar gain. It shows:

  • Device formation using Atlas syntax
  • Specification of a graded SiGe composition fraction
  • Selection of models for SiGe
  • DC simulation for Ic and Ib versus Vbe

The majority of this example is similar to the silicon bipolar Gummel plot example described in the BJT section. This description will focus on the specific SiGe syntax. More details on various types of bipolar simulation can be found in the BJT examples section.

The region statement is used to define the SiGe region in the base of an NPN bipolar transistor. The argument of the 'material' parameter is case-sensitive: SiGe is acceptable, but sige is not. The composition fraction of the area inside of x.min, x.max, y.min and y.max is defined by the x.composition parameter. Outside of this box the Ge composition fraction rolls of linearly to zero over the distance specified by the grad.* parameters. For more details on grad.* parameters, see the Blaze chapter of the manual. For non-linear composition fraction variations, DEVEDIT is needed.

The material parameters for SiGe are selected by material material=SiGe ... . Here the lifetime is set differently for SiGe and Si regions. In this example common models are used between Si and SiGe regions, but this is not compulsory. The material parameter of the models statement can be used to set separate models for each material.

The electrical part of the example is the same as the silicon examples referenced above. The solution file stored at the final voltage can be used to examine the band diagram of the HBT. The statement
enables the conduction and valence band edge energies to be stored in the solution file. This command is recommended for all heterojunction simulations in Blaze.

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.