Subsections
An electron can be scattered from one valley to another one both by acoustical and optical phonons. Intervalley scattering can be treated as a
deformationpotential interaction [30] in the same way as intravalley scattering by optical phonons.
This scattering process is subdivided into ftype and gtype processes. A process is referred to as ftype, if the initial and final orientations are
different, otherwise as gtype process. The transition probability of this mechanism is given by:

(2.115) 
where
is:

(2.116) 
is the equilibrium phonon number of the involved phonon type:

(2.117) 
is the number of possible equivalent final valleys of the same type. For ftype scattering and for gtype scattering .
is the coupling constant,
is the corresponding phonon energy.
The numerical values of the coupling constants and phonon energies [18,20] are shown in Table 2.4.
For this type of scattering there is no separation into f and gtype processes. The scattering rate is given as:

(2.118) 
where
is

(2.119) 
is the equilibrium phonon number of the involved phonon type:

(2.120) 
for the transition between two different orientations and
for scattering within the
same orientation, denotes the corresponding coupling constant and
is the energy of the phonon involved in the scattering
process.
The numerical values of the coupling constants and phonon energies [18,20] for this type of scattering are shown in Table 2.5.
This process involves transitions between all possible valleys in the conduction band. The scattering rate is given by:

(2.121) 
where
is:

(2.122) 
is the equilibrium phonon number of the involved phonon type:

(2.123) 
and
is given as

(2.124) 
Indices and stand for the initial and final valley, respectively, is the number of possible equivalent final valleys, is
the corresponding coupling constant,
is the respective phonon energy,
and
are the energy
minima of the initial and the final valley, respectively.
The numerical values of the coupling constants and phonon energies [18,20] for this type of scattering are shown in Table 2.6.
S. Smirnov: