Every software package contains a full set of examples suitable for that version and are installed with the software. If you see examples here that are not in your installation you should consider updating to a later version of the software. These examples can be used by beginners and advanced users for product evaluation, teaching purposes, and self-training.
Required Modules
Victory Device
- 2D Simulator
This example demonstrates the simulation of a GaN metal-insulator-semiconductor field effect transistor (MISFET) with Piezo Neutralization Technique (PNT).
This example is based on the work of:
K.Ota et al., “A Normally-off GaN FET with High Threshold Voltage Uniformity Using A Novel Piezo Neutralization Technique, ” IEDM 2009, pp. 153-156.
The features of the PNT structure are described below and simulated using Victory Device.
The first feature is an AlGaN buffer layer to realize a normally-off operation. The polarization charges at the interface between the AlGaN buffer and the GaN channel act as virtual p-type doping and contribute to simultaneously increase the Vth and the charge density in the channel.
The second is an Al0.07Ga0.93N PNT layer with an identical Al composition to the buffer layer to achieve high Vth uniformity. Since the PNT and buffer layers have an identical Al mole fractions, the polarization charges formed between these layers are completely cancelled, resulting in a flat band condition throughout the PNT layer. The dependence of Vth on the AlGaN layer thickness under the gate electrode was simulated with Schottky gate structures. For the GaN FETs with the PNT structure, the Vth is not affected by the variation of AlGaN thickness (recess-etch depth), while it varies significantly for the conventional Al0.15Ga0.85N/GaN single heterojunction FETs.
The last one is the 2nd supply layer in the region outside the gate electrode to reduce the on-resistance of the GaN FET. Since the 2nd supply layer is consisted of AlGaN with higher Al composition than that for the 1st supply layer, a large amount of 2DEG is generated in both the channel layer and the PNT layer when the POLARIZATION model is enabled in the MODELS statement. This polarization model accounts for the fact that a layer may not have homogeneous strain, e.g., due to recessed gates, and thus the polarization charge is calculated locally.
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