1
PN JUNCTION
ELECTROSTATICS
ECE335F, Lecture 13
Oct. 8, 2015
2
Last time
Qualitative overview of PN junction operation
Depletion layer
Energy diagram
Built-in potential
Built-in electric field
Today: lets put in some equations and numbers for the
d
1
PN DIODE APPROXIMATIONS
ECE335F, Lecture 17
Oct. 20, 2015
2
Last time Derived IV relation
Current continuity and minority carrier diffusion equation
d 2 p
p
p
=
= 2
2
dx
D p p L p
d 2 n!
n'
n!
=
= 2
2
Dn n Ln
dx
Derived IV relationship of the diode
F
1
REVERSE BREAKDOWN,
FORWARD BIAS
ECE335F, Lecture 15
Oct. 13, 2015
2
Last week
PN junction electrostatics
d E (x)
1. Charge density
=
dx
s
2. Electric field
dV
=E
3. Electrostatic potential
dx
(-ve of shape of the energy bands)
Derived:
Depletion laye
1
CURRENT CONTINUITY,
IV RELATION
ECE335F, Lecture 16
Oct. 15, 2015
2
Last time
Steps for analysis:
1.
Find pN(x) and nP(x)
2.
Find JP,diff(x = xn) and JN,diff(x = xp).
3.
Since J = JN + JP and the current is assumed to be constant in the
depletion region
1
SMALL-SIGNAL MODEL,
OPTOELECTRONIC APPLICATIONS (1)
ECE335F, Lecture 18
Oct. 22, 2015
2
Small-signal model
Apply a time-dependent voltage biased at VDC of the form
V = VDC + v(t), where |v| |VDC|, and analyze the current
Very often v(t) is assumed to
1
METAL-SEMICONDUCTOR
JUNCTIONS: SCHOTTKY DIODES
ECE335F, Lecture 20
Oct. 27, 2015
2
Metal-semiconductor junctions
Two possible behaviours
Resistive Ohmic contact
Rectifying Schottky diode
P
metal
N
metal
3
Definitions
vacuum level, Evac
Work function
TRANSISTORS,
MOS CAPACITOR OVERVIEW
Lecture 22
Oct. 30, 2015
2
Transistors
Transfer-resistor
3 terminals a small signal (current or voltage) in one terminal
controls a much larger signal between the other pair of
terminals
Switching element
Amplifier