ECE 474: Principles of Electronic Devices

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ECE 474Principles of Electronic Devices

• Prof. Virginia Ayres
• Electrical Computer Engineering
• Michigan State University
• ayresv_at_msu.edu

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Lecture 12

• Chp. 02 Nanosystems
• Quantized energy levels Atomic spectra
• Wavelike electrons Davisson-Germer
• Particle-like photons Photoelectric effect
• Wavelike electrons
• What is the wavelength?
• What is the position and momentum?
• Uncertainty principle gt statistical approach
• Examples
• Quantization turns up from wavelike electrons
• Uncertainty principle turns up from wavelike
  electrons
• Really high resolution microscope turns up from
  wavelike electrons

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The wavelength of an electron deBroglie
wavelength
The particle-ness of an electron its envelope
called its modulation
The deBroglie wave is inside the modulation wave
packet
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The wavelength of an electron deBroglie
wavelength
The particle-ness of an electron its envelope
called its modulation
Note this lm nomenclature is from heterodyning.
Heterodyning is when you put two waves with
slightly different frequencies together, getting
the above two-packet envelope.
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The wavelength of an electron deBroglie
wavelength
The particle-ness of an electron its envelope
called its modulation
Two-wave Heterodyning Wave 01 Wave02 2A
cos(1/2 wt -1/2 Dk x) cos(wt-kx)
modulation in x km ½ Dk
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The wavelength of an electron deBroglie
wavelength
The particle-ness of an electron its envelope
called its modulation
Two-wave Heterodyning Wave 01 Wave02 2A
cos(1/2 wt -1/2 Dk x) cos(wt-kx)
modulation in x km ½ Dk
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The wavelength of an electron deBroglie
wavelength
The particle-ness of an electron its envelope
called its modulation
Dx
For Two-wave Heterodyning, the spread of a wave
packet is Dx 2p/Dk.
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The wavelength of an electron deBroglie
wavelength
The particle-ness of an electron its envelope
called its modulation
Dx
However to get a single wave packet, you need to
combine an infinite number of waves whose
frequencies differ infinitesimally from each
other. Infinite means using whats called a
Fourier series. For a Fourier series Dx
1Dk
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The wavelength of an electron deBroglie
wavelength
The particle-ness of an electron its envelope
called its modulation
Dk 1/Dx
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The wavelength of an electronldB and TEM
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The wavelength of an electronldB and TEM
http//www.unl.edu/CMRAcfem/temoptic.htm
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The wavelength of an electronldB and TEM
Potential Difference V ? eV
e-
sample
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The wavelength of an electronldB and TEM
Potential Difference V ? eV
e-
sample
Accelerating voltage
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B.W. Jacobs, V.M. Ayres, M.A. Crimp, and K.
McElroy, Internal Structure of Multiphase
Zinc-Blende Wurtzite Gallium Nitride Nanowires,
Nanotechnology, Vol. 19, No. 40, 405706 (6 pp)
(2008) Impact 3.310
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Examples
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rn
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