Global TCAD Solutions

Predictions based on Physics

GaN HEMT

This example was created using GTS Framework Release 2013. Other releases might need adjustments or have slightly different user interfaces.

This example demonstrates the simulation of GaN devices on the example of a Highelectron mobility Transistor “HEMT”. ToolFolder 001 contains the Structure (compareFigure 1).

Between the different layers of a HEMT a sheet charge forms, therefore following charges
are assumed:

Layer Charge
Cap and Spacer -4.0E+14 cm2
Barrier and Cap: -2.5E+14 cm2
Semiconductor(Channel) and Barrier 9.4E+14 cm2

 

In every Minimos folder the sheet charges have to be set. The following code listing showshow to set the sheet charges in the .ipdm file. A more convenient way is to set it in theGUI on the Details-Page, please see Figure 2. Once the setup is done it can be copied byusing “duplicate ToolFolder” or “Copy Settings” in the next tool menu.

Device : ~DeviceDefaults
{
  Phys
  {
    +Barrier_Semiconductor
    {
      interfaceCharge = "Pure";
      InterfaceCharge
      {
        Pure
        {
          Di = 9.4e+016 "1/m^2";
        }
      }
    }
  }
}


ToolFolder 002 and 003 shows the transfer characteristics using DD and HD Scheme, respectively. For a comparison see Figure 3. ToolFolder 004 shows the output characteristics, see Figure 4.

Figure 6 and 7 show the band edge structure of the biased HEMT. It can be seen that nearly all electrons are below the barrier in the channel. Because the channel is not doped the mobility for electrons is very high. As expected in the off-state all electrons are pushed away from the Gate (Figure 6). In the on-state a channel forms (Figure 7).