Abstract
InGaAs quantum well light emitting diodes (LED) with spin-injecting, epitaxial Fe contacts were fabricated using an in situ wafer transfer process where the semiconductor wafer was transferred under ultrahigh vacuum (UHV) conditions to a metals growth chamber to achieve a high quality interface between the two materials. The spin LED devices were measured optically with applied magnetic fields in either the Faraday or the oblique Hanle geometries in two experimental set-ups. Optical polarizations efficiencies of 4.5% in the Faraday geometry and 1.5% in the Hanle geometry are shown to be equivalent. The polarization efficiency of the electroluminescence is seen to decay as the temperature increases although the spin lifetime remains constant due to the influence of the D’yakonov–Perel’ spin scattering mechanism in the quantum well.
Highlights
High spin polarization devices are necessary for the successful development of semiconductor spintronics [1,2,3]
We show these to be equivalent in terms of the measured optical polarization efficiency
A second system was used to measure the devices in the oblique Hanle geometry, where a small magnetic field is applied at an angle (φ) to the normal to the sample [7, 14, 16] to saturate the Larmor precession, Ωτs 1, where Ω is the Larmor frequency and τs is the spin lifetime
Summary
High spin polarization devices are necessary for the successful development of semiconductor spintronics [1,2,3]. The interface plays an essential role as evidenced by the fact that half-metallic materials (with bulk polarization approaching 100%) do not translate into equivalent high spin polarizations when combined with GaAs devices [7, 8]. In the work presented here, the spin-polarization as a function of temperature using an Fe contact on an InGaAs quantum well LED device is investigated where the transfer between the III–V and metals growth chamber was carried out in situ. The devices measured here were from two different exper imental geometries, the Faraday [10] and the oblique Hanle geometry [14, 16] We show these to be equivalent in terms of the measured optical polarization efficiency.
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