Electrical spin injection in a ferromagnet/tunnel barrier/semiconductor heterostructure

Motsnyi, Vasyl; Boeck, J. De; Das, J.; Roy, W. Van; Borghs, Gustaaf; Goovaerts, E.; Safarov, V. I.

doi:10.1063/1.1491010

Cited by 296 publications

(183 citation statements)

References 17 publications

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“…These data together unambiguously demonstrate that spin-polarized electrons are electrically injected from the Fe contact into the Si heterostructure. The magnitude of P circ from Si is smaller than that typically observed for spin injection from Fe into GaAs(001) quantum wells 13,16,[18][19][20] , although it exceeds some of the earlier reports for GaAs (refs 21,22). This is due in part to the partitioning of the electron spin angular momentum between the photon and phonon for phonon-assisted radiative recombination that typically dominates in indirect-gap materials.…”

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confidence: 45%

Electrical spin-injection into silicon from a ferromagnetic metal/tunnel barrier contact

et al. 2007

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The electron's spin angular momentum is one of several alternative state variables under consideration on the International Technology Roadmap for Semiconductors (ITRS) for processing information in the fundamentally new ways that will be required beyond the ultimate scaling limits of silicon-based complementary metal-oxide-semiconductor technology 1 . Electrical injection/transport of spin-polarized carriers is prerequisite for developing such an approach 2,3 . Although significant progress has been realized in GaAs (ref. 4), little progress has been made in Si, despite its overwhelming dominance of the semiconductor industry. Here, we report successful injection of spin-polarized electrons from an iron film through an Al 2 O 3 tunnel barrier into Si(001). The circular polarization of the electroluminescence resulting from radiative recombination in Si and in GaAs (in Si/AlGaAs/GaAs structures) tracks the Fe magnetization, confirming that these spin-polarized electrons originate from the Fe contact. The polarization reflects Fe majority spin. We determine a lower bound for the Si electron spin polarization of 10%, and obtain an estimate of ∼30% at 5 K, with significant polarization extending to at least 125 K. We further demonstrate spin transport across the Si/AlGaAs interface.The manipulation of carrier spin angular momentum in semiconductors offers enhanced functionality and a new paradigm for device operation 2-4 . Recent calculations 5 indicate that spinbased field-effect transistors can exhibit lower leakage currents and switching energies than those projected for end-of-roadmap complementary metal-oxide-semiconductor devices, significantly reducing heat dissipation, which has been identified as one of the grand challenges facing scaled complementary metal-oxidesemiconductors 1 . Several fundamental properties of Si make it an ideal host for spin-based functionality. Spin-orbit effects producing spin relaxation are much smaller in Si than in GaAs owing to the lower atomic mass and the inversion symmetry of the crystal structure itself. The dominant naturally occurring isotope, Si 28 , has no nuclear spin, suppressing hyperfine interactions. Consequently, spin lifetimes are expected to be relatively long, as demonstrated by electron paramagnetic resonance work on donor-bound electrons 6 and more recent work on free electrons in Si (refs 7,8). In addition, silicon's mature technology base and overwhelming dominance of the semiconductor industry make it an obvious choice for implementing spin-based functionality. Several spin-based Si devices have indeed been proposed, including transistor structures 9,10 and elements for application in quantum computation/information technology 11 .Despite these advantages, efficient electrical spin injection and transport in Si have yet to be demonstrated. Here, we electrically inject spin-polarized electrons from a thin ferromagnetic Fe film through an Al 2 O 3 tunnel barrier into a Si(001) n−i−p doped heterostructure, and observe circular polarization of the electrolumin...

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confidence: 45%

Electrical spin-injection into silicon from a ferromagnetic metal/tunnel barrier contact

et al. 2007

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“…8 One possible route to overcome this impedance mismatch obstacle is to insert a tunneling barrier between the metal and semiconductor. 9,10 First results are already available, and spin injection into GaAs either via a tunnel barrier 11 or a Schottky barrier 12 has been demonstrated. However, the junction properties and injection efficiency are strongly dependent on the metal-barrier interfaces.…”

Section: Spin-injection Device Based On Eus Magnetic Tunnel Barriersmentioning

confidence: 99%

Spin-injection device based on EuS magnetic tunnel barriers

Filip¹,

LeClair²,

Smits³

et al. 2002

Applied Physics Letters

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We propose a spin-valve device consisting of a nonmagnetic semiconductor quantum well, sandwiched between ferromagnetic semiconductor layers that act as barriers. The total conductance through such a trilayer depends on the relative magnetization of the two ferromagnetic-barrier layers which act as “spin filters.” With respect to practical realization, EuS/PbS heterostructures may be a suitable candidate. The magnetoresistance should exceed 100% for a wide range of the thicknesses of both the quantum well and the ferromagnetic barriers. From a fundamental physics point of view, the device may not only give insight into the spin lifetimes of the nonmagnetic layer, but the strong spin accumulation taking place in the quantum well may lead to novel optical and nuclear magnetic resonance properties.

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“…between the ferromagnetic metal and the semiconductor. This method has been experimentally verified on GaAs-based systems [4,5]. However, Si technology is the basis for over 90% of the semiconductor market.…”

mentioning

confidence: 97%