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3.2 Material Models

In this section the models are described that define and distinguish the relevant III-V materials used. Using a similar set of parameters AlGaAs/GaAs and InGaP/GaAs HBTs [207] and in a simplified modeling approach pseudomorphic AlGaAs/InGaAs HEMTs have been simulated using MINIMOS-NT[50]. Special effort was made to obtain an extended and more complete set of parameters for a wide range of material compositions and new materials systems. In the modeling concept applied the ternary materials are composed from their binary constituents using a second order interpolation. Table 3.1 shows the naming convention of the ternary materials and the energetic order of the valleys in k-space as a function of material composition. For Al$ _x$Ga$ _{1-x}$N the investigations are restricted so far to the situation of the $ \Gamma$ valley having a direct band gap due to uncertainties in the band structure [103,158], which is sufficient for all technically relevant AlGaN/GaN HEMTs.


Table 3.1: Minimum valley as a function of material composition.
Material Composition Range Minimum Composition Range Minimum References
  $ x$   $ x$    
Al$ _{x}$Ga$ _{1-x}$As 0-0.45 $ \Gamma$ 0.45-1 X [250]
In$ _{x}$Ga$ _{1-x}$As 0-1 $ \Gamma$ - -  
In$ _{x}$Al$ _{1-x}$As 0-0.3 X 0.3-1 $ \Gamma$ [113]
Al$ _{x}$Ga$ _{1-x}$N 0-0.4 $ \Gamma$ - - [158]




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Next: 3.2.1 Mass Density Up: 3. The Physical Model Previous: 3.1.4 Lattice Heat Flow
Quay
2001-12-21