reference arpes spectra taken using a scienta vuv5k ...groups.mrl.uiuc.edu/chiang/scienta lamp...
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Reference ARPES Spectra Taken Using a Scienta VUV5k Lamp and a Scienta R4000 Analyzer Joseph A. Hlevyack T.-C. Chiang Group University of Illinois-Urbana-Champaign Contact Info.: [email protected] (Joseph A. Hlevyack, Doctoral Candidate)
[email protected] (Prof. Tai-Chang Chiang)
Overview of Operating Conditions and Reference Data for Scienta VUV5k He Lamp (1) Unless indicated otherwise, all data were taken using a Scienta VUV5k He lamp together with a Scienta R4000 analyzer (at a sample temperature of ~18 K). (2) Sample Face to Capillary Tip: ~13 mm (3) Test Sample: 8 QL Bi2Se3 grown on bilayer graphene-terminated SiC(0001).
-The electronic structure of an 8 QL Bi2Se3 film should be similar to that of a cleaved bulk sample, and the spectra that follow were taken along the direction. -The thickness of this film has been calibrated according to XRR measurements.
(4) To get “better” statistics of the Dirac cone, and to test the stability of the Scienta lamp, a number of spectra were taken for ~30 min., but from experience with the lamp, this is generally unnecessary. The discharge of the Scienta lamp is very stable and is not extinguished for the duration of the test measurements (in excess of 4 hours of operation).
(5) Typical Operating Conditions for Scienta Lamp (First/Second Pumping Stage Turbos: 67 l/s each, Monochromator Turbo: 260 l/s):
-First Pumping Stage: 9.3 mTorr; -Second Pumping Stage: 8.1E-7 Torr;-Gas line Pressure: ~16.9 psi (~1.17 bar);-Reflection: 0.2%; -Water Line: ~1.75 l/min.
ΓK
Below are RHEED patterns taken during the sample preparation of Bi2Se3 grown on bilayer graphene-terminated SiC(0001).
Measurement Conditions: (1) Electron Beam Energy: ~8 keV (2) Sample Temperature: Room Temperature
RHEED pattern of graphene-terminated SiC(0001)
RHEED pattern of 8 QL Bi2Se3 (test sample for ARPES measurements)
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Measured spectra at different pass energy and slits; see subsequent slides for details.
Measurement Conditions: (1) Number of Scans: 1 (2) Step Size: 15 meV (3) Angular Mode: Angular14 (14 deg. Window) (4) Monochromator: Specular (Intensity: ~88% He I-α) (5) Step Time: 0.2 s (6) Steps: 106, Total Time for Each Spectra: 21.2 s (7) Sample Temperature: ~18 K NOTE: Skipped pass energy 10 (bulk bands completely washed out at start of scan).
Pass Energy: 1 eV Data File: 20170727155030
Pass Energy: 2 eV Data File: 20170727155252
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Pass Energy: 5 eV Data File: 20170727155456
Slit 2: Width: 2.5 mm, Length: 30 mm; “Slit 700”; Straight
Slit 3: Width: 1.5 mm, Length: 30 mm; “Slit 600”; Straight 4 0 -4
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Pass Energy: 1 eV Data File: 20170727160158
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Pass Energy: 5 eV Data File: 20170727160316
Measurement Conditions: (1) Number of Scans: 1 (2) Step Size: 15 meV (3) Angular Mode: Angular14 (14 deg. Window) (4) Monochromator: Specular (Intensity: ~88% He I-α) (5) Step Time: 0.2 s (6) Steps: 106, Total Time for Each Spectra: 21.2 s (7) Sample Temperature: ~18 K NOTE: Skipped pass energy 10 (bulk bands completely washed out at start of scan).
Slit 4: Width: 0.8 mm, Length: 25 mm; “Slit 500”; Curved 4 0 -4
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Pass Energy: 1 eV Data File: 20170727161248
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Pass Energy: 2 eV Data File: 20170727161325
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Pass Energy: 5 eV Data File: 20170727161402
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Pass Energy: 10 eV Data File: 20170727161508
Measurement Conditions: (1) Number of Scans: 1 (2) Step Size: 15 meV (3) Angular Mode: Angular14 (14 deg. Window) (4) Monochromator: Specular (Intensity: ~88% He I-α) (5) Step Time: 0.2 s (6) Steps: 106, Total Time for Each Spectra: 21.2 s (7) Sample Temperature: ~18 K
Slit 5: Width: 0.5 mm, Length: 25 mm; “Slit 400”; Curved 4 0 -4
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Pass Energy: 1 eV Data File: 20170727162424
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Pass Energy: 2 eV Data File: 20170727162534
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Pass Energy: 5 eV Data File: 20170727162710
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Pass Energy: 10 eV Data File: 20170727162916
Measurement Conditions: (1) Number of Scans: 1 (2) Step Size: 15 meV (3) Angular Mode: Angular14 (14 deg. Window) (4) Monochromator: Specular (Intensity: ~88% He I-α) (5) Step Time: 0.2 s (6) Steps: 106, Total Time for Each Spectra: 21.2 s (7) Sample Temperature: ~18 K
Slit 6: Width: 0.3 mm, Length: 25 mm; “Slit 300”; Curved
Pass Energy: 1 eV Data File: 20170727163912
Pass Energy: 2 eV Data File: 20170727163948
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Pass Energy: 5 eV Data File: 20170727164025
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Pass Energy: 10 eV Data File: 20170727164059
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Pass Energy: 20 eV Data File: 20170727164 318
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Measurement Conditions: (1) Number of Scans: 1 (2) Step Size: 15 meV (3) Angular Mode: Angular14 (14 deg. Window) (4) Monochromator: Specular (Intensity: ~88% He I-α) (5) Step Time: 0.2 s (6) Steps: 106, Total Time for Each Spectra: 21.2 s (7) Sample Temperature: ~18 K
Slit 7: Width: 0.2 mm, Length: 25 mm; “Slit 200”; Curved 4 0 -4
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Pass Energy: 1 eV Data File: 20170727165803
Pass Energy: 2 eV Data File: 20170727165839
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Pass Energy: 5 eV Data File: 20170727165916
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Pass Energy: 10 eV Data File: 20170727165949
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Pass Energy: 20 eV Data File: 20170727170030
Measurement Conditions: (1) Number of Scans: 1 (2) Step Size: 15 meV (3) Angular Mode: Angular14 (14 deg. Window) (4) Monochromator: Specular (Intensity: ~88% He I-α) (5) Step Time: 0.2 s (6) Steps: 318, Total Time for Each Spectra: 21.2 s (7) Sample Temperature: ~18 K
Spectra taken at optimal settings, including one using the monochromator at pure He I-α (hν = 21.218 eV) with “Slit 600” (3rd straight: Width: 1.5 mm, Length: 30 mm). Roughly, there is generally more background for spectra taken under specular light (Intensity: ~88% He I-α) compared to spectra taken under pure He I-α light.
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Measurement Conditions: (1) Number of Scans: 25 (2) Step Size: 5 meV, (3) Pass Energy: 5 eV (4) Angular Mode: Angular14 (5) Monochromator: Specular (Intensity: ~88% He I-α) (6) Step Time: 0.2 s, Steps: 375 (7) Total Time for Spectra: 31.25 min. (8) Data file: 20170727150810 (9) Sample Temperature: ~18 K
Measurement Conditions: (1) Number of Scans: 30 (2) Step Size: 5 meV, (3) Pass Energy: 10 eV (4) Angular Mode: Angular14 (5) Monochromator: pure He I-α (hν = 21.218 eV) (6) Step Time: 0.2 s, Steps: 375 (7) Total Time for Spectra: 37.5 min. (8) Data file: 20170727212402 (9) Sample Temperature: ~18 K
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Intensity at Random Point (-3 deg., 16.6 eV): ~60 x 103 (a.u.)
Intensity at Random Point (-3 deg., 16.6 eV): ~2 x 103 (a.u.)
Monochromator (Complete Separation of Spectral Lines) Reference Spectra: Slit: 3rd Straight; “Slit 600”; Width: 1.5 mm, Length: 30 mm. These are near Fermi-level scans using complete separation of He lines.
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Measurement Conditions: (1) Pass Energy: 10 eV, (2) Step Size: 5 meV, (3) Mono.: He I-α, (4) Data File:20170727212402, (5) Steps: 375, (6) Number of Scans: 30, (7) Total Time: 37.5 min., (8) Sample Temperature: ~18 K
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Measurement Conditions: (1) Pass Energy: 10 eV, (2) Step Size: 5 meV, (3) Mono.: He I-β, (4) Data File: 20170727195145, (5) Steps: 395, (6) Number of Scans: 30, (7) Total Time: 39.5 min., (8) Sample Temperature: ~18 K
Measurement Conditions: (1) Pass Energy: 10 eV, (2) Step Size: 5 meV, (3) Mono.: He II, (4) Data File: 20170727184636, (5) Steps: 375 (6) Number of Scans: 30 (7) Total Time: 37.5 min. (8) Sample Temperature: ~18 K
Monochromator (Complete Separation of Spectral Lines) Reference Spectra: Slit: 3rd Straight; “Slit 600”; Width: 1.5 mm, Length: 30 mm. These are valence scans taken over a larger energy range (vs. those found on the previous slide).
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Measurement Conditions: (1) Pass Energy: 5 eV, (2) Step Size: 25 meV, (3) Mono.: He I-α, (4) Data File: 20170727205515, (5) Steps: 256, (6) Number of Scans: 30, (7) Total Time: 17 min., (8) Sample Temperature: ~18 K
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Measurement Conditions: (1) Pass Energy: 5 eV, (2) Step Size: 25 meV, (3) Mono.: He I-β, (4) Data File: 20170727203242, (5) Steps: 252 (6) Number of Scans: 30 (7) Total Time: 16.8 min. (8) Sample Temperature: ~18 K
Measurement Conditions: (1) Pass Energy: 10 eV, (2) Step Size: 25 meV, (3) Mono.: He II, (4) Data File: 20170727192456, (5) Steps: 276 (6) Number of Scans: 30 (7) Total Time: 18.4 min. (8) Sample Temperature: ~18 K
These spectra are from the previous two slides, but the kinetic energy was converted to binding energy for ease of comparison. (Slit: “Slit 600,” 3rd straight)
Pass Energy: 10 eV Mono.: He II Data File: 20170727184636
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Pass Energy: 10 eV Mono.: He II Data File: 20170727192456
Pass Energy: 10 eV Mono.: He I-β Data File: 20170727195145
Pass Energy: 5 eV Mono.: He I-β Data File: 20170727203242
Pass Energy: 10 eV Mono.: He I-α Data File: 20170727212402
Pass Energy: 5 eV Mono.: He I-α Data File: 20170727205515
Below are reference data taken with the “cheap” UVS 10/35 UV lamp and the Scienta VUV5k (Slit: 3rd straight: Width: 1.5 mm, Length: 30 mm).
Measurement Conditions: (1) Number of Scans: 25 (2) Step Size: 5 meV (3) Angular Mode: Angular14 (14 deg. Window) (4) Monochromator: Specular (Intensity: ~88% He I-α) (5) Step Time: 0.2 s, Steps: 375 (6) Total Time for Spectra: 31.25 min. (7) Data file: 20170727150810 (8) Sample: 8 QL Bi2Se3 (9) Sample Temperature: ~18 K
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Measurement Conditions: (1) Number of Scans: 30 (2) Step Size: 5 meV (3) Angular Mode: Angular14 (14 deg. Window) (4) Monochromator: pure He I-α (hν = 21.218 eV) (5) Step Time: 0.2 s, Steps: 375 (6) Total Time for Spectra: 37.5 min. (7) Data file: 20170727212402 (8) Sample: 8 QL Bi2Se3 (9) Sample Temperature: ~18 K
Measurement Conditions: (1) Number of Scans: 50 (2) Step Size: 5 meV (3) Angular Mode: Angular14 (14 deg. Window) (4) Step Time: 0.2 s, Steps: 375 (5) Total Time for Spectra: 62.5 min. (6) Data file: 20170124201125 (7) Sample: 7 QL Bi2Se3, according to TM (not XRR adjusted and is definitely thinner). (8) Sample Temperature: ~18 K
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Scienta VUV5k Scienta VUV5k SPECS UVS 10/35 6 4 2 0 -2 -4 -6
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