1. Molecular Beam Epitaxy (MBE) C Tom Foxon
School of Physics and Astronomy, University of Nottingham
Nottingham 2015

2. What is MBE?
Growth of epitaxial films on a hot substrate from molecular beams under ultra-high vacuum conditions.
III-V Semiconductors ( also used for gp IV, II-VIs, metals, oxides etc)
Typical growth rates: one monolayer/sec (equivalent to a pressure of 10-6Torr)
Nottingham 2015

3. MBE systems old and new
Nottingham 2015

4. MBE schematic
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5. MBE cells schematic Nottingham 2015
Typical effusion cell for Al, Ga etc.
Nottingham 2015

6. Growth of GaAs from Ga & As2
C T Foxon and B A Joyce, Surface Science 64 (1977) 293
Nottingham 2015

7. Growth dynamics - RHEED
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8. Growth dynamics - RHEED
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9. Scanning tunnelling microscopy
Atomic resolution using a tip
close to the surface
Nottingham 2015

10. Large area STM images Initial surface before growth after 3
Large area STM images Initial surface before growth after 3.5 MLs deposited Sudijono et al, J Crystal Growth 280 (1993) 247
Nottingham 2015

11. Superlattices All SL laser QW 8 MLs AlAs 8MLs GaAs 1ML= 0.28nm
Nottingham 2015

12. MBE at Nottingham (1991 with John Orton)
AlGaInN or III-Nitrides
Spintronics - GaMnAs, CuMnAs etc.
Amorphous III-Arsenide Nitrides
Free standing AlGaN
Photocathodes – with Photek
Graphene-Boron Nitride
Nottingham 2015

13. Nottingham 2015

14. Active species from the plasma
OED
(745nm)
869nm
Source A
Nottingham 2015

15. Morphology for growth on sapphire
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16. Growth on GaN substrates
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17. CuMnAs after annealing
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18. Low temperature MBE growth of GaNAs
RMS roughness is ~0.2nm
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19. Measurements at Berkeley – Yu et al
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20. Free standing cubic AlGaN
Nottingham 2015

21. The worlds hotest MBE
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22. Epitaxial graphene by heating SiC
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23. Graphene grown from carbon on sapphire
Nottingham 2015

24. Graphene grown from carbon on sapphire
Nottingham 2015

25. Summary
MBE gives excellent control of composition and thickness, with both in-situ and ex-situ characterisation
In-situ monitoring with mass spectrometry for growth kinetics, with RHEED and STM for growth dynamics.
Since coming to Nottingham, we have extended the materials grown by MBE to include, nitrides, spintronics amorphous nitrides, bulk AlGaN and photocathodes (at Photek).
The latest venture is graphene-boron/nitride
Nottingham 2015