7. Simulation Studies

This chapter treats simulation studies on issues of state-of-the-art industrial HEMT technology development. Fig. 7.1 shows a three-dimensional image of a typical multi-finger HEMT with critical areas highlighted.

Figure 7.1: Three-dimensional image of critical simulation issues in HEMTs(1)=Thermal boundary conditions, (2)= Heterojunction carrier transport, (3)= ($\delta$-)doping activation, (4) = high field effects, (5) = gate currents.

The thermal boundary conditions (1) were already addressed in Chapter 6. The heterojunction carrier transport (2) is key to understand and simulate HEMTs. The ($\delta$-)doping (3) determines the available carrier sheet charge density ${\it n}_{\mathrm{sheet}}$ in the channel. High field effects (4) such as e.g. impact ionization are to be accounted for in the device, which eventually allows to simulate gate currents ${\it I}_{\mathrm{G}}$ (5).