2.3.3 The Split-Off Band
Although the split-off band is parabolic, the apparent effective mass in this band will also exhibit a temperature dependence due to the energy displacement at k = 0. The energy of a hole in the third band is given by
E=Ev - A- A (2.20)
where A is the split-off energy (= 0.044eV), and A is one of the inverse mass band parameters. Substituting equation (2.20) into equations (2.11) through (2.13), and then equating to equations (2.6), (2.9) and (2.10) for the split-off band, we obtain
m 02A~
m exp (-3(2.21)
D3 A3
A 3/2
fT3F2 exp(-E2)d 2
0
m f T33/2exp(_)d
m* 0 0 (2.23)
H 3 A - TA3 C2 e x p (- 2 )d 2
MI f _3 2 C3/2 exp( _ 2)d 2
where c2= c - A/k0T.
The combined hole density-of-state effective mass can be determined by assuming that the total number of holes in the valence band is equal to the sum of the holes in the individual bands