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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