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TEORI DASAR HUBUNGAN SEMIKONDUKTOR
Hamzah Afandi, Antonius Irianto danBetty Savitri
Source: Millman, Jacob, Grabel, Arvin, Microelectronics, Mc. Graw Hill Int. Ed., 1994.
Robert Boylestad, Louis Nashelsky Sixth Edition; Prentice Hall,1997.
Review: Semiconductor Properties Variation– Intrisic Concentration vs Temperature:
– Mobility vs Temperature: ; mn=2.5, mp=2.7
(100<T<400K)
– Mobility vs Electric Field intensity:
kTEi
GTAn /30
2 0
mT 0
21
0 nnnn 0 1
0 nn ~ 107 cm/s
103 V/cm 104 V/cm
Review: Currents in semiconductor
• Drift Current: )pn pq(nJ
pn pnq
Drill:
Calculate the conductivity of an extrinsic semiconductor with donor atom’s concentration of 1016 atom/cm3 (at 300K)!
10
.
.
1045.1
475
15002
2
xni
sVcm
p
sVcm
n
REVIEW: The Physics of Electronics
Carrier’s Concentration in extrinsic Semiconductor
pn = ni2
nNpN AD
D
2i
D N
n pNn ;
Mass-Action Law
Charge Density should maintain electric neutrality of crystal
For n-type semiconductor, NA = 0; thus:
A
2i
A N
n nNp ; For p-type semiconductor, ND = 0; thus:
Review: Currents in semiconductor
• Diffusion Current:
2pp A/m dp/dx D q -J
Concentration
xx0 x1
p(x0)
p(x1)
dx
dp
Jp
Dp = Diffusion Constant of Carrier
Einstein Relationship between D and
Tn
n
p
p VDD
VT
q
kTVT 11600
Review: Currents in semiconductor
• Total Current:
)2ppp (A/m dp/dx D q -pqJ
Concentration
xx0 x1
p(x0)
p(x1)
dx
dp
Jp
)2nnn (A/m dn/dx D q nqJ
Review: Graded semiconductor
dp/dx D q -pqJ ppp
Concentration
xx1 x2
p(x1)
p(x2)
dx
dp
V21
p1 p2
Jp = 0; in open circuited steady state condition
dx
dp
pV
dx
dV
mVdx
dp
pV
dp/dx Vq -pq0
VD
T
T
Tpp
Tpp
1
)/(1
)(ln
1
2
121
2
1
2
1
Vp
pVV
pdp
VdV
T
x
x
T
x
x
pn JUNCTION DIODE
Hamzah Afandi, Antonius Irianto danBetty Savitri
Source: Millman, Jacob, Grabel, Arvin, Microelectronics, Mc. Graw Hill Int. Ed., 1994.
Open Circuited Junction
p type n type
Semiconductors Semiconductors
ElectronsHoles
neutral neutral
Open Circuited JunctionJunction Formation
p type n type
Junction
Depletion RegionSpace Charged Region
Open Circuited JunctionJunction Formation
p type n type
Charge Density (V)
Depletion RegionSpace Charged Region
-Wp Wn
Open Circuited JunctionJunction Formation
p type n type Field Intensity ()
Depletion RegionSpace Charged Region
-Wp Wn
')'(
)( dxxv
xx
Wp
E
Open Circuited JunctionJunction Formation
p type n type Electrostatic Potential (V)
Depletion RegionSpace Charged Region
-Wp Wn
V = 0
V0
')'()(V dxxxx
Wp
E
Open Circuited JunctionJunction Formation
p type n type
Potential Barrier of electrons(V)
Depletion RegionSpace Charged Region
-Wp Wn
V = 0V0
Closed Circuited JunctionForward Biased pn Junction
p type n type
Depletion RegionSpace Charged Region
Closed Circuited JunctionForward Biased pn Junction
p type n type
Depletion RegionSpace Charged Region
Closed Circuited JunctionReverse Biased pn Junction
p type n type
Depletion RegionSpace Charged Region
Closed Circuited JunctionReverse Biased pn Junction
p type n type
Depletion RegionSpace Charged Region
Closed Circuited JunctionReverse Biased pn Junction
p type n type
Depletion RegionSpace Charged Region
VOLT-AMPERE CHARACTERISTIC
(A) 1
T
DV
V
SD II
ID
VD
IS (A Scale)
V-VZ
Cut-inOffest
Turn-onBreakdown
= 2 (Si) = 1.5 (Ge)
Diode Circuit Analysis: Load-Line Concept
ID
VD
+
_VAA
R
VD
ID+
_
QIDQ
VDQ VAA
VAA /R
Solve for:VAA = 3 VR = 2 K
(A) 110.5 507
mV
V
D
D
I
CALCULATIONEXAMPLES
Given in class