Materials Science and Engineering - Electronic and Mechanical Properties of Materials Part 3 pot
Materials Science and Engineering - Electronic and Mechanical Properties of Materials Part 1 doc
... R
c2
& R
c3
⇒ therefore no IR contribution to V
23
R
s
( 2 -3 ) = v
23
/I = σ
-1
(d
23
/A) = ρ (d
23
/A)
(Note: ρ-resistivity is inverse of σ−conductivity)
© H.L. Tuller-2001
3. 225
20
How ... Tuller-2001
For R
9
3. 225
9
Equation of Motion - Impact of Collisions
Assume:
• probability of collision in time dt = dt/τ
• time varying field F(t)
v(t+dt...
Materials Science and Engineering - Electronic and Mechanical Properties of Materials Part 5 ppt
... Eg=1.1eV, and let µ
e
and µ
h
be approximately equal at 1000cm
2
/V-sec (very good Si!).
σ~10
10
cm
-3
*1.602x10
-1 9
*1000cm
2
/V-sec=1.6x10
-6
S/m, or a resistivity ρ of about 10
6
ohm-m max. ... ~10
20
cm
-3
– Add 10
18
cm
-3
donors to Si: n~N
d
–n~10
18
cm
-3
, p~10
2
(n
i
2
/N
d
)
• Can change conductivity drastically
– 1 part in 10
7
impurity in a...
Materials Science and Engineering - Electronic and Mechanical Properties of Materials Part 10 pps
... 12 13
10
-7
10
-6
10
-5
10
-4
Y-cut
σ
0
= 2.1 S cm
-1
E
A
= 105 kJ mol
-1
10
4
/T [1/K]
σ
[S cm
-1
]
900 800 700 600 500
T [°C]
13
3. 225
13
© H.L. Tuller-2001
Gas Sensors and ...
•Smart sensors
3. 225
14
© H.L. Tuller-2001
Microhotplate
7
4
3. 225
7
© H.L. Tuller-2001
0 5 10 15 20 25 30 35
1E-5
1E-4
1E -3
0,01
0,1
T = 850°C
X=0. 03...
Materials Science and Engineering - Electronic and Mechanical Properties of Materials Part 9 pps
... (Ωcm)
-1
)
T = 800 °C
log(pO
2
/ bar)
0.995 1,005
-1 6 -4 0
-5
-4
-3
-2
-1
0
1
donor
acceptor
-2 0 -1 2 -8
donor doped
acceptor doped
2
3. 225
15
Designer Wavelengths
Variation of ... Wavelengths
Variation of band-gap energy with composition x of In
1-x
Ga
x
As.
© H.L. Tuller, 2001
3. 225
16
Band-Gap Colors
Mixed crystals of yellow...
Materials Science and Engineering - Electronic and Mechanical Properties of Materials Part 3 pot
... Fitzgerald-1999
)
)
)
3
3.225
5
Effect of Temperature (T>0): Coupled electronic- thermal properties in conductors
• Electrons at the Fermi surface are able to increase energy: responsible for
properties
• ... are λ=h/p~10
-8
cm in size
• Certain wavelengths of valence electrons will diffract!
© E. Fitzgerald-1999
3. 225
8
Diffraction Picture of the Origin of Band G...
Materials Science and Engineering - Electronic and Mechanical Properties of Materials Part 6 pps
... when you join these together?
© E. Fitzgerald-1999
3. 225
12
-
-
+
+
+
+
Holes diffuse
Electrons diffuse
+
+
+
+
-
-
-
-
+
+
+
+
-
-
+
+
+
+
An electric field forms due to ... Fitzgerald-1999
Potential Wells - Heterojunction Lasers
Energy bands of a light-emitting diode under forward bias for a double
heterojunction AlGaAs-GaAs-AlGaAs stru...
Materials Science and Engineering - Electronic and Mechanical Properties of Materials Part 8 pdf
... Tuller, 2001
or
0
3
ε
α
orc
N
T
T
=
Fig. 1. The Curie-Weiss law illustrated for (Ba,Sr)TiO
3
From L.L. Hench and J.K. West, Principles of Electronic
Ceramics, Wiley, 1990, p. 2 43.
1
33
00
=
=
c
kT
CNN
εε
α
c
c
TT
T
−
=
3
χ
3. 225
2
• ... H.L. Tuller, 2001
W
6
3. 225
7
Characteristics of Optical Fiber
© E. Fitzgerald-1999
3. 225
8
Characteristics of...
Materials Science and Engineering - Electronic and Mechanical Properties of Materials Part 4 pps
... numbers are:)
n=1,2 ,3, …
=0,1,2,…,n-1
m
l
=- , - +1,…,0,…, ,
(m
s
=+ or - 1/2)
l
l
l
l
0
-1 3. 6eV
U(r)
© E. Fitzgerald-1999
)
in
-1
3. 225
9
Diffraction Picture of the Origin of Band Gaps
Probability ... Electron Model
© E. Fitzgerald-1999
5
3. 225
5
Metals and Insulators
•E
F
in mid-band area: free e-, metallic
•E
F
near band edge
–E
F
in or near kT...
Materials Science and Engineering - Electronic and Mechanical Properties of Materials Part 11 potx
... negative
Rule of Thumb:
5.1
radius) 2(atomic
distance cinteratomi
2
>≡
a
r
r
J is a function of distance!
8
3. 225
8
© E. Fitzgerald-1999
Ferromagnetism
M
T
T
C
() ( )
() ( )
1. 4-1 .3
0 .3 7-0 .33
≈−∝
≈−∝
−
γχ
β
γ
β
TTT
TTTM
C
C
H
B=H+4πM
‘normal’ ... material
Material Type
χ
Paramagnetic +10
-5
-1 0
-4
Diamagnetic -1 0
-8
-1 0
-5
Ferromagnetic +10
5...
Materials Science and Engineering - Electronic and Mechanical Properties of Materials Part 2 pot
... e
-i(kx-ωt)
are all waves
e
-i(kx-ωt)
is the complex one and is the most general
real
imaginary
A
Acosθ
iAsinθ
θ
e
iθ
=cosθ+isinθ
© E.A. Fitzgerald-1999
1
3. 225
11
Wiedmann-Franz ... Fitzgerald-1999
5
3. 225
25
Experimental Hall Results on Metals
• Valence=1 metals look like
free-electron Drude metals
• Valence=2 and 3, magnitude
and sign suggest problems
© E.A...
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