A Normally-on Vertical GaN FET (CAVET) I-V Characteristics

ganfetex20.in : A Normally-on Vertical GaN FET (CAVET) I-V Characteristics

Requires: Victory Device or Atlas
Minimum Versions: Victory Device 1.14.1.R or Atlas 5.28.1.R

This example demonstrates TCAD computation of Id-Vd, Id-Vg, and transconductance gm-Vg characteristics of a gallium nitride (GaN) field-effect transistor (FET) called CAVET (Current Aperture Vertical Electron Transistor).

This example is based on the following reference paper:

[1] S. Chowdhury, M. H. Wong, B. L. Swenson, and U. K. Mishra, "CAVET on bulk GaN substrates achieved with MBE-regrown AlGaN/GaN layers to suppress dispersion", IEEE Electron Device Letters, vol.33, Jan. 2012, pp.41-43.

The input deck provided with this example can be run by either Victory Device or Atlas simulator, just by changing the solver name in the command go victorydevice into go atlas . It shows that both Victory Device and Atlas device simulators can be fully compatible in terms of input commands, producing same results, and allowing easy transition between Atlas and Victory Device.

This example demonstrates:

  • Construction of the Vertical GaN-FET structure using the device simulator syntax
  • Material and models parameter specification
  • Simulation of Id-Vg, gm-Vg, and Id-Vd characteristics
  • Display of the results in TonyPlot

The device under consideration is a normally-on Vertical AlGaN/GaN HEMT of type CAVET (Current Aperture Vertical Electron Transistor). The main concept here is that the polarization charge is calculated using the built-in models as specified by the polarization parameter on the model statement.

First, the initial solution is obtained (for zero bias), which includes also calculation of the 2D Electron Gas (2DEG) sheet density.

Then, the Id-Vg transfer characteristics are computed, for several selected Vds voltages, from which the transconductance gm-Vg characteristics are extracted. Next, the Id-Vd output characteristics are computed, for several selected Vgs voltages.

The family of I-V curves is plotted using the TonyPlot tool. All the computed I-V curves compare quite well with the CAVET experimental curves published in the reference paper [1] (Fig. 2).

You can plot similar overlaid plots yourself if you use Overlay feature in TonyPlot . The transconductance gm (dId/dVg) curve can be plotted using Display > Functions... feature in TonyPlot.

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.