Band structure of the epitaxial Fe∕MgO∕GaAs(001) tunnel junction studied by x-ray and ultraviolet photoelectron spectroscopies

Abstract

The electronic band structure in the epitaxial Fe/MgO/GaAs(001) tunnel junction has been studied by X-ray and ultraviolet photoelectron spectroscopy measurements. The Schottky barrier height (SBH) of Fe on MgO/GaAs heterostructure is determined to be 3.3±0.1eV, which sets the Fe Fermi level about 0.3eV above the GaAs valence band maximum. This SBH is also exactly the same as that measured from Fe on MgO monocrystal. After Fe deposition, no band bending change is observed in MgO and GaAs underlayers. On the contrary, Au and Al deposition lead to clear variation of the band bending in both MgO and GaAs layers. This effect is analyzed as a fingerprint of defects states at the MgO/GaAs interface.

Large Perpendicular Magnetic Anisotropy in Ta/CoFeB/MgO on Full-Coverage Monolayer MoS2 and First-Principles Study of Its Electronic Structure

“…Our calculated values of the Fe work function and the MoS2 ML electron affinity and band gap energy are indeed of 3.91 eV, 3.65 eV and 1.74 eV, respectively (while the values of 4.5 eV 52 , 4 eV 53,54 and 1.8 eV 1 have respectively been measured in experiments). A similar charge transfer has also been experimentally observed in the Fe/MgO/GaAs system 55 . The charge transfer induced by the insertion of MgO can effectively reduce the Schottky barrier height for FM/2D contact 31,56,57 , which is in favor of the spin-polarized electron injection from the FM metal to the 2D conduction band.…”

Exchange-Driven Spin Relaxation in Ferromagnet-Oxide-Semiconductor Heterostructures

“…The band offset at the interface ( Fig. 1 (c), inset) is determined by previous studies using x-ray and ultraviolet photoelectron spectroscopies to study the band structure of Fe/MgO/GaAs tunnel junction [21]. A control sample is grown with a similar structure but without the Fe/MgO layer, and both samples are mounted face-down on 100 µm thick sapphire wafers so that the n + -GaAs substrates can be 4 removed by selective wet etching using the In0.5Ga0.5P layer as a chemically-selective etch stop [22].…”

Light helicity detection in MOS-based spin-photodiodes: An analytical model

“…Moreover, we note that even if a fully general quantitative model should require band bending effects to be included, leading to a device structure typical of a diode (nonlinear current-voltage characteristics), our model works quite well for spin-PDs based on MgO barriers, because of Fermi level depinning at the interface between MgO and some semiconductors, such as Ge 42 and GaAs. 24 The total current flowing across the device (J) is composed by two contributions: (i) a light-independent term (J 0 ), produced by the application of the external voltage DV, and (ii) the photocurrent (J ph ) due to the light illumination, dependent on the light intensity reaching the SC and on the SC characteristics (absorption, quantum efficiency, and recombination). In a n-type SC, J 0 is an electron current, while in J ph both electrons and holes are involved, because of the charge neutrality of the photo-generated pairs.…”