XRD Procedure 2014
XRD Procedure 2014
VDD, August 2014 Word Doc form of the procedure:
Open XRD program
Instrument > connect
Select diffracted beam optics, path 1
Make sure shutter is closed, and open XRD chamber
Switch detector to alternative position (with analyzer cube)
Insert 1/4 inch slit in beam path (no slit in detector)
Load sample
Set Psi to 90 degrees
Use single sided tape to attach sample to backing wafer and backing wafer to stage
Mount sample at center of stage
Close chamber doors
Turn on x-ray generator
Under the 'X-ray' tab, change the generator power to 45 kV and 40 mA (or whatever the new values are in the XRD manual).
Alignment procedures
Change all position and angle settings to zero: User settings > sample offsets > Click "Set New = 0"
Do a 2thetascan (only moves detector). Start with a wide range:
Range = 3 (Use range = 7 if system is very misaligned)
Step Size = 0.1
Time/Step = 0.1
Right click > Peak mode > move to peak
After initial wide scan, narrow down range and increase resolution:
Range: 2
Step Size: 0.01
Time/Step: 0.1
Right click> Peak mode > move to peak
User settings > sample offsets > Click "Set New = 0"
Z scan (intersect sample with beam)
Set Z ~8.5
Range: 2
Step Size: 0.001
Time/Step: 0.1
Right click > Move mode > Set edge where decay is ~1/2 of high intensity
Close the shutter, open XRD chamber, and insert 1 mm slit on detector
Set instrument settings
Unit cell for substrate material and (0 0 4) for (h k l)
Align Omega - initial alignment
Range: 3 (Use 5 is system is very misaligned)
Step Size: 0.01
Time/Step: 0.1
Right click > Peak mode > Move to peak
User settings > sample offsets > change offsets to these values so all plots line up:
| GaAs | GaSb |
2theta | 66.0479 | 60.7285 |
omega | 33.0239 | 30.3642 |
Align Z - second round (this step is necessary when the system is very misaligned)
Range: 1
Step Size: 0.001
Time/Step: 0.1
Right click > Move mode > Set edge where decay is ~1/2 of highest intensity
Align Omega and Psi
Omega
Range: 0.1
Step Size: 0.001
Time/Step: 0.5
Psi
Range: 5 (start with 10 if very misaligned)
Step Size: 0.1
Time/Step: 0.5
Align 2theta again
Range: 0.5 (Try 1 if out of alignment)
Step Size: 0.001
Time/Step: 0.1
Back to Omega and Psi alignment
Go back and forth between Omega and Psi until they are both aligned
Always start and end with omega scan
Use log scale for best results
If a double curve appears, align consistently to peak of taller curve
Should get intensities >100K (1M is best) counts
| Omega | Psi |
Range | 0.1 | 5 |
Step Size | 0.001 | 0.1 |
Time/Step | 0.5 | 0.5 |
Set user data:
User setting > change sample offsets to these values (so all plots line up)
| GaAs | GaSb |
2theta | 66.0479 | 60.7285 |
omega | 33.0239 | 30.3642 |
Quick Omega-2theta scan to find diffraction pattern
Range: 5
Step Size: 0.004
Time/Step: 0.1
Detailed Omega-2theta scan for analysis
Range: 1 (Narrow down as necessary)
Step Size: 0.001
Time/Step: 0.5
Should still have peak intensities in ~100K-1M range otherwise there is an alignment issue
After scan, save plots as .xrdml files
When done scanning, change unit cell to 'None' and all angles and positions to zero
Change Psi to 90 to change samples
When finished with scanning all the samples, change the x-ray generator power to 15 kV and 5mA (or whatever new values are now- see manual)
Leave the generator on
To do analysis on the saved files, open .xrdml files in X'Pert Data Viewer
File > convert > PAN & comma separated (2 files)
For easy access, backup the files to the lase share folder:
\\lase.mer.utexas.edu\share
User: share