Biomedical Engineering Reference
In-Depth Information
(a)
(b)
OV1, B doped
OV2, B doped
4 × 10
-4
3 × 10
-4
2 × 10
-4
1 × 10
-4
1 × 10
-5
5 × 10
-6
0 × 10
0
0 × 10
0
-1 × 10
-4
-2 × 10
-4
-3 × 10
-4
-4 × 10
-4
-5 × 10
-6
-1 × 10
-5
-15 -10
-5
0
5
10
15
-15 -10
-5
0
5
10
15
Voltage (V)
Voltage (V)
FIGURE 4.9
Room temperature current-voltage measurements between two symmetric electrodes across the surface of the
diamond films. (From Ye, H.,
Phys. Status Solidi A Appl. Res.
, 193, 462, 2002. With permission.)
prove if this technique is valid on this type of film. The Cole-Cole plots of boron-doped
single-crystalline diamond films from 50°C to 300°C are shown in Figure 4.11a-c. Figure
4.11a presents the data measured at 50°C showing the presence of a single semicircular
response, with some scatters at the low frequency impedance range (right end). Similar
data are shown in Figure 4.11b for the temperature range from 125°C to 200°C. The diam-
eter of the semicircles reduces dramatically with the temperature increasing: (a) 50°C and
100°C, (b) 125°C and 200°C, and (c) 225°C and 300°C.
It is found that each Cole-Cole plot shows only one depressed semicircle. The single
semicircle indicates that only one primary mechanism exists for the electrical conduction
within the diamond film at temperatures below 300°C. The depressed semicircles make
their centers on a line below the real axis, which indicates the departure from the ideal
Debye behavior [1]. The diameter of each semicircle indicates the electrical resistance of
-5
y
= 2.2793 + -4.1688
x
R
= 0.99981
-10
-15
-20
E
= 0.36 eV
-25
-30
2
3
4
5
6
7
8
1000/
T
(K
-1
)
FIGURE 4.10
DC current-temperature measurement using TSC chamber from -185°C to 256°C. Voltage is set to 50 V as power
supply. Linear curve fitting from -134°C to 147°C shows the sample has a DC activation energy of 0.36 eV. OV1
is from up to down, and OV2 is from left to the right as shown in Figure 4.9. (From Ye, H.,
Phys. Status Solidi A
Appl. Res.
, 193, 462, 2002. With permission.)
