Biomedical Engineering Reference
In-Depth Information
Read diode
p
+
n
I (ORV)
n
+
Si
10
20
N
1
5 × 10
16
N
2
10
13
x
(µm)
(a)
0
1
2
3
5
4
Area = ∫ε d
x
3
2
w
1
0
x
x
A
(b)
0
b
1
2
3
10
8
6
∫<
a
> d
x
= 1
4
2
0
(c)
x
0
1
2
3
FIGURE 2.9
Read diode (a) doping profile (p-n-i-n), (b) ionized integrand at avalanche breakdown and (c)
Avalanche region. (After Bhasin, K.P. et al., Monolithic optical integrated control circuitry for
GaAs MMIC-based phased arrays,
Proc. SPIE
578, September, 1985.).
current peak occurs not at the AC voltage peak (Φ = π/2) but at the point
when the AC voltage becomes negative (Φ = π).
This is because of the avalanche phenomena. Avalanche occurs when
electron-hole pairs are created. These free carriers have enough energy that
when they impact with other electrons, ionization occurs, creating even
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