4.3.1 Effective Mass and Band Edge Energy
 
In [47] and [48] the effective masses as well as the band edge energies of electrons and holes for AlGaAs and InGaAs are given, respectively. The effective masses of electrons and holes for Al_yGa_1­yAs read
 

(36)

 
and for In_xGa_1­xAs
 

.

(37)

 
The parameters for (36) and (37) are given in  Table 4.1.
 

Table 4.1 Parameters for the effective masses of Al_xGa_1­xAs and In_yGa_1­yAs

Parameter	AlyGa1-yAs	InxGa1-xAs
[m0]	0.067	0.079
[m0]	0.083	-0.038
[m0]	-	-
[m0]	0.080	0.120
[m0]	0.080	-0.099
[m0]	-	0.030

The lattice temperature T_L [K] and Al mole fraction y dependent E_g of Al_yGa_1­yAs reads:
 

(38)

 

(39)

 

(40)

 

(41)

 
The temperature dependent band edge energy for In_xGa_1-xAs reads
 

,

(42)

where the band edge energy of GaAs is given by (38)­(41) for x = 0 and  by
 

.

(43)

 
The parameters E_g, a, and b for GaAs, AlAs, and InAs and the "bowing" parameter C are given in  Table 4.2.
 

Table 4.2 Parameters for the band gap energy models

5.58	8.78	2.76
220	322	83
1.521	2.891	0.42
C [eV]	0.475

As described in Chapter 2 the current in a HEMT channel is conducted in a strained quantum well. The effective conduction band offset DE_{C eff} of the unstrained bulk material described by the above models is changed due to strain and quantum effects. To account for these effects in the simulation E_g of the channel material is adapted according to the calculations shown in Section 2.2.
 

• 4.3.2 Mobility

   
Next: 4.3.2 Mobility Up: 4.3 Physical Parameters Previous: 4.3 Physical Parameters