pn Junction Diode:

1
Chapter 6. pn Junction Diode I-V
Characteristics
2
pn Junction I-V Characteristics
3
(No Transcript)
4
(No Transcript)
5
(No Transcript)
6
(No Transcript)
7
Quantitative pn Diode Solution
8
(No Transcript)
9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
J(x) -J(x)
J(x) J(x)
18
Quantitative pn Diode Solution
19
(No Transcript)
20
Ideal I-V

• Ideal I-V
• Reverse bias (VAlt0)
• Forward bias (VAgt0)

log scale
21
Saturation Current

• Saturation current
• Depends on material
• ni.Si ? 1010 cm-3, ni.Ge ? 1013 cm-3 ? I0.Ge
  / I0.Si ?
• Asymmetrically doped junction
• p-n
  diodes
• n-p
  diodes
• As a general rule, the heavily doped side of an
  asymmetrical junction can be ignored in
  determining the electrical characteristics of the
  junction.

22
Exercise 6.1
23
Carrier Currents

• Minority carrier current densities in QNR decay
  exponentially away from the depletion region
  edges.
• Within the depletion region, JN and JP are drawn
  constant at their respective depletion-edge
  values.
• The total current density in the depletion
  region is the sum of JN and JP and it is constant
  everywhere inside the diode.
• The majority-carrier current densities in QNR
  are obtained by subtracting the minority-carrier
  current densities from the total current density.

24
Carrier Concentrations Forward Bias

• Forward bias increases the minority carrier
  concentration.

Low-level injection ? approximately constant
majority carrier concentration
Decay due to recombination
Decay due to recombination
straight line
25
Carrier Concentrations Reverse Bias

• A reverse bias of only a few kT/q effectively
  reduces to zero the minority carrier
  concentrations at the edges of the depletion
  region.

sink for minority carrier
sink for minority carrier
26
Exercise 6.3
27
Exercise 6.4