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Lecture 14
Current-Potential Curves at
Semiconductor Electrodes
Reference.
1. R. Memming, Semiconductor Electrochemistry, Wiley-VCH, 2000 (e-book)
2. A.J. Bard and L.R. Faulkner, Electrochemical Methods: Fundamentals and
Applications, Wiley, 2001
3. J. O’M. Bockris, A.K.N. Reddy, and M. Gamboa-Aldeco, Modern Electrochemistry,
Kluwer Academic/Plenum Publishers, 2000
Lecture note
http://les.kaist.ac.kr/B_Lecture
Recap: I-V Curves at Metal Electrodes
Recap: Metal-Electrolyte Interface
At equilibrium
Under polarization
Potential Controls Activation Energy
Recap: Bias Changes the Fermi Level
I-V Curves of Semiconductor Electrodes
Band Bending of Semiconductor
n-type Semiconductor-Electrolyte Interface
𝑜
𝑈𝑟𝑒𝑑𝑜𝑥 − 𝑈𝑟𝑒𝑑𝑜𝑥
=
𝑘𝑇
𝑐𝑜𝑥
ln(
)
𝑒
𝑐𝑟𝑒𝑑
The activation energy is independent
of the relative concentration of the
redox system and also independent of
the externally applied voltage!
Quantitative Derivation of Current-Potential
Curves
Conduction Band Processes
jc+: an electron transfer rate associated from a
filled state in a redox system to an empty state
in a SC.
jc-: an electron transfer rate associated from a
filled state in a SC to an empty state in a redox
system.
Valence Band Processes
jv+: an electron transfer rate associated from a
filled state in a redox system to an empty state
in a SC.
with
jv-: an electron transfer rate associated from a
filled state in a SC to an empty state in a redox
system.
We will define another rate constants for each equations so that
I-V Relationship
At equilibrium
Conduction band process
I-V Curves of Semiconductor Electrodes
Light-induced Process
Next Meeting
Current-Potential Curves at Semiconductor Electrodes: Part II