advsemi_lec6 2013-04-24
TRANSCRIPT
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Advanced
Semiconductor
Devices
Lecture 6
Advanced
Semiconductor
Devices
Lecture 6
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V. Ariel 2013 Advanced Semiconductor Devices Lecture 6
Lecture outline
Review
Basic two-terminal MOS structure
Regions of operation
Solution for charges and potentials
Approximations for regions of operation
Surface potential model in moderate inversion
MOS Capacitor
MOS Capacitor in moderate inversion
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Voltage and charge balance
Total charge in semiconductor body
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Electron charge density
Surface electron charge density
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Charge inversion
Inversion charge basis of current transport
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Flatband
Accumulation
Depletion and inversion
Regions of operation
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Charge density and Poisson equation
Solution for semiconductor
charge
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Charge density and Poisson equation
Charge density as a
function of distance
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Solution of Poisson equation
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Solution of Poisson equation
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Solution for surface electric field
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Solution for semiconductor charge
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Semiconductor charges andpotentials
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Solution for gate voltage
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Depletion
Condition for depletion
Approximation for gate voltage in depletion
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Inversion
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Gate voltage and surface potential ininversion
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Weak inversion
On the border of moderate inversion
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Weak inversion
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Strong inversion
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Moderate inversion
Need a simple solution for semiconductor charges and
potentials in moderate inversion !!!
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V. Ariel 2013 Advanced Semiconductor Devices Lecture 6
Moderate inversion
Need a simple solution for semiconductor charges and
potentials in moderate inversion !!!
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Moderate inversion
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MOS Capacitor
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MOS C it i l ti
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MOS Capacitor in accumulation
Semiconductor charge capacitance exponentially increasing
for large negative surface potential
Therefore, in accumulation
MOS Capacitor in depletion and
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MOS Capacitor in depletion andweak inversion
MOS Capacitor in depletion and
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MOS Capacitor in depletion andweak inversion
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MOS C it i d t d
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Obtained MOS capacitor model in all regions of operation
Can obtain model parameters from experimental
measurements of gate capacitance
MOS Capacitor in moderate andstrong inversion