PC4250Introduction to Surface Analysis Techniques

References for Surface Science

Main text:• Vickerman (ed) Surface Analysis, Wiley 1997

Further Reading:• Woodruff & Delchar, Modern Techniques of Surface

Science, CUP 1986• Wiesendanger, Scanning Probe Microscopy and

Spectroscopy, CUP 1994

On-line resources:• http://www.uksaf.org/tutorials.html

Ref: http://www.er.doe.gov/production/bes/scale_of_things.html

Surface Science Lab NUSUHV systems:• VG ESCA MkII/SIMSLAB• Cameca IMS 6f Magnetic sector

SIMS) • VT-STM/XPS/LEED system + growth

chamber with molecular beam & reactive atom sources [+ cryogenic STM]

• Soft X-ray synchrotron end station on SINS beamline [+ growth chamber + STM/AFM]

• [EXAFS endstation]

Surface Techniques• Most physics techniques can be classified as scattering experiments:

a particle is incident on the sample, and another particle (not necessarily the same) is detected after the interaction with the sample.

• Surface Physics is no exception: we can think of an incident Probe X and a Response Y. If we understand the nature/physics of the scattering, then we can interpret the experiment and deduce the corresponding characteristics of the sample.

Probe

X

Response

Y

Electrons (E0,k0, ..spin s) Electrons (E,k, ..spin s)

Radiation (0,k0, ..polarisation) Sample Radiation (,k, ..polarisation)

Atoms (E0,k0,Z) Atoms (E,k, Z')

Ions (E0,k0, Z) Ions (E,k, Z')

Overview of techniques

Reasons for surface sensitivity• The incident particle or the probe particle has a short

mean free path, . – XPS - emerging electrons in the energy range 50-1000 eV have

for inelastic scattering in solids, of order 1 nm or less. – LEED - both the incident and the emergent electrons have short

mean free paths for energy loss processes– SIMS - emergent ions have a very high probability of being

neutralised if they do not originate very near the surface.

• The sample has a large surface to volume ratio. – allows us to extract surface information from techniques which

are not particularly surface sensitive. – use powdered/exfoliated samples and perform heat capacity or

other thermodynamic measurements, X-ray or neutron scattering– use thin film samples and concentrate on the surface-related

contribution; e.g. TEM done on thin films around 10-100 nm thick.

Primary Particle Probes