240
8 Transport
Fig. 8.16 Time
dependence of the electron
velocity at room
temperature upon a
step-like electric field
(40 kV/cm) for GaAs
(dash-dotted line), InP
(dashed line) and
In 0.53 Ga 0.47 As (solid line)
0.2
8
6
4
2
0 0
0.4
0.6
0.8
7
In Ga As
0.53
0.47
InP
GaAs
Fig. 8.17 Electron and
hole transitions for impact
ionization close to the
threshold energy.
Ionization is triggered by a
an electron and b a split-off
hole of velocity v i
(a)
e
hh
lh
so
k
E
v i
E g
(b)
e
hh
lh
so
k
E
v i
E g
E
thr
hh =
1 +
m hh
m e + m hh
E g ,
(8.32)
is larger because of the larger hole mass.
The threshold for impact ionization triggered by a split-off hole (shown schematically in Fig. 8.17b)
is [771]
E
thr
h =
1 +
m so (1 − 0 /E g )
2 m hh + m e − m so
E g .
(8.33)
8 Transport
Fig. 8.16 Time
dependence of the electron
velocity at room
temperature upon a
step-like electric field
(40 kV/cm) for GaAs
(dash-dotted line), InP
(dashed line) and
In 0.53 Ga 0.47 As (solid line)
0.2
8
6
4
2
0 0
0.4
0.6
0.8
7
In Ga As
0.53
0.47
InP
GaAs
Fig. 8.17 Electron and
hole transitions for impact
ionization close to the
threshold energy.
Ionization is triggered by a
an electron and b a split-off
hole of velocity v i
(a)
e
hh
lh
so
k
E
v i
E g
(b)
e
hh
lh
so
k
E
v i
E g
E
thr
hh =
1 +
m hh
m e + m hh
E g ,
(8.32)
is larger because of the larger hole mass.
The threshold for impact ionization triggered by a split-off hole (shown schematically in Fig. 8.17b)
is [771]
E
thr
h =
1 +
m so (1 − 0 /E g )
2 m hh + m e − m so
E g .
(8.33)