Cobalt-Al2O3-silicon tunnel contacts for electrical spin injection into silicon

Abstract

The resistance of Co–Al2O3–Si tunnel contacts for electrical spin injection from a ferromagnet into silicon is investigated. The contacts form a substantial Schottky barrier, 0.7eV, which plays a dominant role in the electronic transport. On Si with a low doping concentration (∼1015cm−3), the contact resistance is affected by the Al2O3 tunnel barrier only in the forward bias. In the reverse bias (the spin injection condition), the Schottky barrier results in a very high contact resistance, ∼102Ωm2. While the contact resistance is improved to ∼10−2Ωm2 using Si with a high doping concentration (∼5×1019cm−3), it is still about five to six orders of magnitude higher than the value needed for resistance matching to silicon.

Electric field effects on spin accumulation in Nb-doped SrTiO3 using tunable spin injection contacts at room temperature

“…Compared to conventional n-doped degenerate semiconductors the rather large rectification of the Co/Nb:SrTiO 3 interface is surprising. 16,17 This originates from the large dielectric permittivity of Nb:SrTiO 3 ($330 at room temperature) widening the depletion region. Standard analysis of the temperature dependent I-V measurement shows the charge transport to be dominated by thermally assisted fieldemission.…”

Tunnelling anisotropic magnetoresistance due to antiferromagnetic CoO tunnel barriers

“…1(c) , the red and blue curves are the corresponding X-ray reflectivity measurement and the simulated plot (PANalytical, X’Pert Reflectivity) respectively for such a bi-layer, from which the so-obtained CoO thickness was determined. The Néel temperature of the so-fabricated films is ~240 K 21 . A 3.3 nm AlO x tunnel barrier was obtained by deposition of a 2.5 nm Al film followed by 30 minutes plasma oxidation.…”

Spin injection from Fe into Si(001):Ab initiocalculations and role of the Si complex band structure

“…Recently, however, electrical spin injection into Si has also been demonstrated both via electrical spin detection 8,9,10 and optical detection 11 with impressively large spin coherence length, reaching up to 350 µm. 10 The present work was motivated by the increasing experimental activity in the direction of spin injection and manipulation in Si, 8,9,10,11,12,13 as well as by arguments for advantages of spin transport in Si. 14 Based on densityfunctional calculations we examine the possibility of direct spin injection from Fe into Si, with the Schottky barrier of Si used as the necessary tunneling barrier.…”

“…7 Most works have focused on injection into GaAs, [5][6][7][8] where the current polarization can be detected optically in GaAs/ AlGaAs/GaAs quantum wells or electrically in lateralgeometry experiments. 8 Recently, however, electrical spin injection into Si has also been demonstrated via electrical spin detection, [9][10][11][12] nonlocal electrical detection, 12 and optical detection, 13 with impressively large spin coherence length, reaching up to 350 m. 11 The present work was motivated by the increasing experimental activity in the direction of spin injection and manipulation in Si, [9][10][11][12][13][14][15] as well as by arguments for advantages of spin transport in Si. 16 Based on density-functional calculations we examine the possibility of direct spin injection from Fe into Si, with the Schottky barrier of Si used as the necessary tunneling barrier.…”