1 nano 225 intro to nano/microfabrication other characterization techniques
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NANO 225 Intro to Nano/Microfabrication
Other Characterization Techniques
Composition Analysis• Wet Chemistry Techniques
– Liquid or Vapor Phase– Chromatography – Spectroscopy in UV-Vis region
• Physics Techniques– Solid Phase– Inputs Particle (electrons) or X-rays– In Vacuum– Nano-friendly
X-ray Emission Spectroscopy
Characteristic x-ray out
ejected electron
e- transition
e- beam in
Energy Dispersive Spectroscopy (EDS) Wavelength Dispersive Spectroscopy
(WDS)
X-Ray Fluorescence Spectroscopy
Characteristic x-ray out
ejected photoelectron
e- transition
x-ray in
XRF
• Bulk analysis of elemental composition– ppm or ppb sensitivity
• ~1mm beam diameter• Quick quantitative analysis
– Metals– Ceramics– Plastics
• Thickness measurements– plating– coatings
Surface Chemical Analysis
• Electron Spectroscopy for Chemical Analysis (ESCA) = X-ray Photoelectron Spectrometry (XPS)
• Auger Electron Spectrometry• Secondary Ion Mass Spectrometry
photon or particle emission
Electron Spectroscopy for ChemicalAnalysis (ESCA=XPS)
x-ray in
photoelectron out
• Photoelectric effect• 1906 Einstein
ESCA, XPS
• Electron escape depth (1-3nm) “surface analysis”
• Chemical Shifts – identification of surface functions
ESCA Chemical Shifts
• Example PET
Auger Electron Spectroscopy
• Surface analysis– Can use electrons or x-rays
• Mostly electron beam– Scanning electron beams
allow imaging as well– First derivative plots
characteristic x-ray re-absorbed
e- transition
x-ray or electron in
characteristic Auger electron
Sputter Depth Profiling
Acquire spectrumSputterAcquire Sputter……. Depth profile
auger
ESCA/XPS
Secondary Ion Mass Spectrometry
• Atomic Billiards
• Input: particles Ar+, Ga+, Cs+, C60
• Output: atomic or molecular fragments
SIMS
• Example PET.
X-ray Diffraction
n=2dsin(Bragg’s Law
X-ray Diffraction
• Data
Diffractogram
Camera images
X-ray Diffraction
• Structure determination
Vibrational Spectroscopy for Organic Structure Characterization
• Infrared Spectroscopy– IR absorption spectrum
• Fourier Transform data collection (FT-IR)
• Raman Spectroscopy– Raman effect– Laser (single ) excitation of vibration modes
• near-IR, Vis, near-UV
Energy causes molecular vibrations (phonons)
Infrared Spectroscopy• Continuous IR light in• Absorption band out
h1h2h3
hn-1hn
hx
h1h2h3
hn-1hn
• Polar groups are active
Raman Spectroscopy• Single wavelength in• Rayleigh and Raman scattered light out
hx
hx-nhx-2hx-3
hx-(n-1)hx-n
hx
• Nonpolar groups are active
• Rayleigh: elastic• Raman: inelastic (Stokes / Antistokes)
Infrared (Vibrational) Spectroscopy
Analysis of organic molecules or covalently bonded inorganics
Raman and IR Spectra• Example PET
Raman
IR
Properties of Interest
• Electrical• Mechanical• Optical• Thermal
Electrical Properties
• Conductivity– = en
• Hall effect– Mobility measurement
• Capacitance – Voltage profile– Carrier concentrations
Electrical Properties
• Dielectric constant (permittivity)• Dielectric strength• Magnetic permeability
Band Structure
• Valence and Conduction bands• Optical spectroscopy
– Optical gap in UV-Vis
Mechanical Properties• Tensile testing
– Stress-strain curves• Stress=modulus · strain (Hooke’s Law)
– Modulus
Nano-indentation• Nanometer-scale stress-strain curves
Load
(m
N)
Displacement (nm)
Thermal Properties
• Coefficient of thermal expansion• =1/V (V/T)
• Heat Capacity• C = Q/T
• Thermal conductivity• = Q/t (L/AT)
• Melting point• Crystallization point• Glass Transition
Optical Properties
• Index of refraction n = c/v• Extinction coefficient
– ellipsometry
• Absorption and emission spectrum