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
|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
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).