semiconductor the integral takes on an approximate value, and the specific near-surface
resistance looks like
1
11
()
1
22
0
(
)
,
s
yw
sn
ns
D
R
q
nL
e
−
−
=+
(8)
and for a hole semiconductor at significant negative values of the surface potential
s
y
the near-surface active resistivity is described by
1
11
()
22
0
(
)
,
s
yw
sp
ps
D
R
q
pL
e
−
−
=+
(9)
where w−
the concentration of active gases on the sensor. The analysis of
dependence of near-surface active resistivity on surface potential for electronic
semiconductor shows that at significant positive values
s
y, when there is a large excess
of electrons in the near-surface layer of enrichment, this excess of electrons will
determine near-surface resistivity, exponentially depends on the index, which is equal
to half of the value
s
y. At decrease
s
y
at first the growth of near-surface resistance
according to this law is observed. In the area of small positive values
s
y
of active
resistance growth it slows down, because the charge of the spatial charge layer is
becoming increasingly important for the charge of ionized donors.
Let's move on to the determination of specific capacity (pF/cm
2
) of the near-
surface layer of the spatial charge of the semiconductor gas sensor. The connection
between the charge and the potential is nonlinear, which determines the differential
capacity of the spatial charge layer. From the solution of the Poisson equation and the
general determination of the capacity, we obtain the value of the specific capacity of
the spatial charge [10]
()
()
2
1
1
.
(
)
(
)
(
)
.
2
(
(),,)
s
s
yw
yw
iD
прзар
s
qnL
e
e
С
kTfyw
−
−
−
+
−
+
+
−
=
(10)
For an own semiconductor, when
1
=
and
0
=, the expression (10) is much
simpler
(
)
()
()
2
.
1
()
()
2
1
.
2
2
ss
ss
y
w
y
w
iD
spch
y
w
y
w
qnL
e
e
C
kT
e
e
−
−
−
=
−+
(11)
The analysis of the formula (11) shows that the differential capacity of the spatial
charge takes the minimum value
0,
s
y=
when there is no bending of the energy zones.
Its value increases with both positive and negative values of the surface potential.
At values
3
s
y
the differential capacity increases proportionally
1
exp
2
s
y
. In the
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