Fast Nuclear Spin Hyperpolarization of Phosphorus in Silicon

1
Fast Nuclear Spin Hyperpolarization of Phosphorus
in Silicon
E. Sorte, W. Baker, D.R. McCamey, G. Laicher, C.
Boehme, B. Saam Department of Physics, University
of Utah
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Silicon doped with Phosphorus
3
Introduction
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Introduction
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Energy Splitting in Magnetic Field
H0
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Relaxation Times
but
?Ee 240 GHz (electric Zeeman) ?En 147 MHz
(nuclear Zeeman) A 117 MHz (hyperfine
interaction)

• Tx returns the spin populations n2 and n3 to
  thermal equilibrium with the phonon reservoir

• T1 returns the spin populations n4 and n3 / n1
  and n2 to thermal equilibrium with the lattice

1 D. Pines, J. Bardeen, C. Slichter, Phys. Rev.
106, 489 1957
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Temperature

• Constant illumination generates new charge
  carriers, leading to steady state with constant
  density of hot electrons
• As hot electrons cascade toward the lattice
  temperature, they emit phonons at constant rate.

G.Feher, Phys. Rev Lett 3, 135 (1959)
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Mechanism
9
?X
Mechanism
10
?X
Mechanism
B8.5T
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?X
Mechanism
12
?X
Mechanism
13
?X
Mechanism
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?X
Mechanism
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Experimental - EPR
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Experimental - EDMR
EDMR at different temperatures
EDMR at T 1.37 K Xe discharge lamp
D. R. McCamey, J. van Tol, G. W. Morley, C.
Boehme, eprint arXiv0806.3429v1 (2008)
17
Conclusion
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Future Experiments

• NMR on 31P nucleus to actually see the nuclear
  polarization.

19
Experimental - EDMR vs. ESR
Comparison of polarization measured using EDMR vs
EPR at different intensities of light (Hg
discharge) at T 3 K.
Hg discharge has higher spectral temperature,
yielding higher polarizations (P-24 at 3K vs
-6 at 3K for Xe lamp) independent of intensity
for most part.
Polarization with ESR ? 45 that measured with
EDMR