188
7 Electronic Defect States
Fig. 7.8 Electron spin
resonance signal from As
and P in Ge with the
magnetic field H parallel to
[100], T ≈ 1.3 K. Adapted
from [579]
Table 7.2 Binding energies E b
D of Li and group-V donors in elemental semiconductors. Data for carbon from [580].
All values in meV
Li
N
P
As
Sb
C
1700
≈500
Si
33
45
49
39
Ge
9.3
12.0
12.7
9.6
Table 7.3 Binding energies E b
D of donors in GaAs (data from [581]), GaP (data from [582]) and GaN (low concentration
limits, data from [583, 584]). All values in meV
V site
III site
GaAs
S
5.854
C
5.913
Se
5.816
Si
5.801
Te
5.786
Ge
5.937
GaP
O
897
Si
85
S
107
Ge
204
Se
105
Sn
72
Te
93
GaN
O
39
Si
22
Ge
19
in germanium. The multiplets distinguish the nuclear spins I = 3/2 for arsenic (
75 As) and I = 1/2
for phosphorus (
31 P) [579].
The donors are typically distributed statistically (randomly) in the solid. Otherwise their distribution
is called clustered. The concentration of donors is labeled N D and usually given in cm
−3 .
The concentration of donors populated with an electron (neutral donors) is denoted by N
0
D , the
concentration of ionized donors (positively charged) is N
+
D . Other conventions in the literature label
the concentrations N 1 and N 0 , respectively:
N 1 = N
0
D = N D f e (E D )
(7.23a)
N 0 = N
+
D = N D (1 − f e (E D )) ,
(7.23b)
with f e (E D ) = [1 + exp(E D − E F )]
−1 . For the sum of these quantities the condition
N D = N
+
D + N
0
D
(7.24)
holds.