ee130/230a discussion 4
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EE130/230A Discussion 4. Peng Zheng. Illumination of a Semiconductor with Light. (Refer to Discussion 3.). EE130/230A Fall 2013. Schottky Contact Energy Band Diagrams :. EE130/230A Fall 2013. Ideal M-S Contact: F M > F S , n-type. Band diagram instantly after contact formation:. - PowerPoint PPT PresentationTRANSCRIPT
EE130/230A Discussion 4
Peng Zheng
Illumination of a Semiconductor with Light
EE130/230A Fall 2013
(Refer to Discussion 3.)
Schottky Contact Energy Band Diagrams:
EE130/230A Fall 2013
Ideal M-S Contact: FM > FS, n-type
FF MBn
Band diagram instantly after contact formation:
Equilibrium band diagram:Schottky Barrier Height:
EE130/230A Fall 2013
qVbi = FBn– (Ec – EF)FB
W
n
Ideal M-S Contact: FM < FS, n-type
EE130/230A Fall 2013
Band diagram instantly after contact formation:
Equilibrium band diagram:
Ideal M-S Contact: FM < FS, p-type
MBp FF GE
Band diagram instantly after contact formation:
Equilibrium band diagram:Schottky Barrier Height:
EE130/230A Fall 2013
qVbi = FBp– (EF – Ev)FB
W
p-typesemiconductor
FBp
EE130/230A Fall 2013
Ideal M-S Contact: FM > FS, p-typep-typesemiconductor
Equilibrium band diagram:
Band diagram instantly after contact formation:
Summary
EFEc
Ev
EF
Ec
EvEF
Ev
EF
EcEv
R.F. Pierret, Semiconductor Fundamentals, p. 481
EE130/230A Fall 2013
)(2
D
Abis
qNVVW
)(2
A
biAs
qNVVW
WAC s /
For rectifying contacts:
small-signal capacitance
Schottky Contact to p-type Silicon with NA = 1016 cm-3 and FBp = 0.4 eV, VA=0V
EE130/230A Fall 2013
Schottky Contact to p-type Silicon with NA = 1016 cm-3 and FBp = 0.4 eV, VA=0V
EE130/230A Fall 2013
W0.52 μm
qVbi = FBp– (EF – Ev)FB
p-type SiM
Ev
EF
Ec
Eo
FM=4.77 eVcSi=4.05 eV
0.195 eV0.4eV=FBp
Schottky Contact to p-type Silicon with NA = 1016 cm-3 and FBp = 0.4 eV, VA=-0.2V
EE130/230A Fall 2013
Once Vbi and NA are known, FBp can be determined:
22
)(21AqNVV
C sA
Abi
A
VBpFBVFBpbi ln)(
NNkTEEqV FF
Using C-V Data to Determine FB
Abi
sA
AbiA
s
ss
VVqNA
VVqN
AWAC
22
EE130/230A Fall 2013
2
1C
AV
Good luck to Quiz 1