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XPert Epitaxy SoftwareVersion 3.0
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Xpert Epitaxy Functionality

• Graphics for single scans, area scans and wafer
  maps
• Peak finding and labelling for single and area
  scans
• Results from rocking curves and maps
• Rocking curve simulation
• Orientation and unit cell calculations

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New Features in Version 3

• Simulation of hexagonal nitride alloy layers with
  choice of substrate
• Modelling of relaxed interfaces and diffuse
  scattering
• Plotting up to six area scans in one window
• Extraction of line scans at any angle
• Smoothing of single scans
• Summary results for rocking curves

released November 1999
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Plotting Single Scans

• Load from Xpert database or from file
• Linear/square root/log
• Degrees /relative seconds
• Zooming

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Editing options

• Removing or adding scans to current window
• Editing header
• Adding text
• Smoothing

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Finding and labelling peaks

• Peak position marked automatically or using
  cursor
• Substrate, Layer and Fringe labels used by
  Results menu
• Peak list display

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Defaults for single scans

• Folders
• Single plot options
• Palettes
• Use relative seconds
• Peak finding
• Wafer map settings

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Sample Files

• Sample files contain information about
  heteroepitaxial layer structures
• Rocking curves are simulated using the
  information in the sample file
• The information is also used by the Results menu

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Sample Files Materials Supported

• Materials supported
• Diamond e.g. Si, Ge
• Zinc blende e.g. GaAs, InP, AlSb
• Hexagonal nitrides AlN, GaN and InN
• Sapphire and silicon carbide substrates

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Layers and Substrates (1)

• Single layers with or without composition grading
• grading options none, linear, convex or concave
• Superlattices, and superlattices within
  superlattices
• In-plane rotation for nitrides on sapphire
• Relaxed interfaces

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Layers and Substrates (2)
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Layers and Substrates (3)
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Versatile sample editing
Tree view of current sample T1 - GaN layers
linked by thickness B1 - alloy layers linked by
thickness and composition
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Rocking curve simulation

• Based on the work of Professor Paul Fewster
• Uses Takagi-Taupin equations for diffraction by
  distorted crystals
• Full data base of materials parameters and X-ray
  scattering factors supplied
• Convolution functions for high resolution
  monochromators and double crystal diffractometers

Note Simulation is not available in XPert
Epitaxy Graphics
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Convolution
(Adding instrumental/sample effects)

• Monochromator type
• Background
• Counting statistics
• Sample curvature
• Diffuse scattering

Convolution can be performed as part of the
simulation process or applied after simulating
the diffracted intensity
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Simulating rocking curves
Optional mismatch plot
Range and step size in degrees or seconds
Rocking curves with and without convolution
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GaN on Sapphire
Experiment First simulation Second simulation
10 well nitride device on sapphire
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Defaults for simulations

• Default substrate and layer combinations for all
  six substrate types
• Default simulation and convolution settings
• Automatic saving

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Results from Rocking Curves

• d-spacing mismatch
• Results summary
• Layer mismatch
• Layer composition
• Layer thickness
• Superlattice period
• Sample curvature

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Superlattice Period
Fringe spacing and period averaged over all
marked satellites
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Results Summary for Rocking Curves

• Composition, mismatch and layer thickness
  calculated together
• Edit substrate and layer materials directly or
  use sample file
• Print out on a single sheet

Box for editing substrate and layer materials
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Updating sample files
Results used to update sample
Calculated results
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The Log

• Send results to log
• Send sample details to log
• Send simulation details to log
• Print out from log
• Save as text file from log

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Plotting area scans

• Load from XPert database or from file
• Up to six scans per window
• Linear/square root/log intensity scaling
• Angle scales or reciprocal lattice units
• Zooming
• Semi-automatic peak find

Bitmap (angles)
Contours (reciprocal lattice units)
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Multiple area maps
new plotting functionality

• Plot up to 6 maps in a window
• Use
• when you do not want to collect data between
  peaks
• when you have not collected a large enough area
  on the first attempt
• to plot scans collected with different optics
  together

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Peak Find

• Use semi automatic peak find
• Label peaks to be analysed

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Parallel Perpendicular Mismatch

• Mark substrate and layer peaks
• Determine mismatch in two directions from a
  single asymmetrical map
• Determine tilt between substrate and layer planes

In reciprocal space
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Parallel Perpendicular Mismatch
Angle plot
Example Relaxed GaInAs on GaAs
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Editing options

• Removing or adding scans to current window
• Extracting single scans
• Extracting area scans
• Projecting onto axis
• Editing header
• Adding text

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Using the Extraction Line

• Extract lines scans at any angle from maps
• Extract Q scans from reciprocal space maps

extraction line
pull on handles to change angle and length
extraction angle
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Defaults for area plots

• Area plot options
• Scan treatment options
• Folders
• Manual levels
• rlu values
• Palettes

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Wafer Maps

• Peak parameters and results from a regular array
  of rocking curves
• View contours, values or both
• Linear or manual contour levels
• Editable outline shape for wafer

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Orientation and Unit Cell Determination

• Calculate orientation from positions of measured
  peaks
• Calculate unit cell from position of measured
  peaks

Uses the same lattice parameter data as the
XPert Data Collector
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XPert Epitaxy 3.0

• Plotting and analysis software
• for XPert PRO users
• interested in sample perfection