Strain-compensated AlInGaAs–GaAsP superlattices for highly polarized electron emission

Abstract

Spin-polarized electron emission from the first superlattice photocathodes developed with strain compensation is investigated. An opposite strain in the quantum well and barrier layers is accomplished using an InAlGaAs/GaAsP superlattice structure. The measured values of maximum polarization and quantum yield for the structure with a 0.18 µm-thick working layer are close to the best results reported for any strained superlattice photocathode structure, demonstrating the high potential of strain compensation for future photocathode applications. An analysis of the photoemission spectra is used to estimate the parameters responsible for the polarization losses.

Evaluation of spin-flip scattering in chirality-induced spin selectivity using the Riccati equation

“…However, very high spin polarised photocurrents have been reached from solid targets. Subashiev et al [35] developed a photocathode consisting of a InAlGaAs/GaAsP superlattice structure which produced spin polarised currents with a spin polarisation of up to P = 84%. Such a large range for P 0 should be more than sufficient to observe or at least accurately interpolate the reachable spin polarisation P * by the node in the function P (P 0 ) − P 0 .…”

Highly Effective Polarized Electron Sources Based on Strained Semiconductor Superlattice with Distributed Bragg Reflector

“…The working layer of the first structure is based on the strain compensated InAlGaAs-GaAsP SL [9], whereby the composition of the GaAsP barrier layers is chosen to have opposite (tensile) strain from that of the InAlGaAs quantum well layers. The second photocathode is based on the InAlGaAs-AlGaAs SL with strained quantum wells [4].…”

Investigation of photoemission of polarized electrons from stressed superstructures

“…Such photocathodes also provide high values of the quantum photoelectron yield (the number of emitted electrons per one absorbed photon) and long lifetime (the time during which the number of photoelectrons decreases by a factor of e). The photocathodes based on the GaAs/GaAsP and InGaAs/GaAlAs superstructures with stressed quantum wells, superstructures with stressed barriers based on GaAs/AlInGaAs, and the so-called compensated superstructures based on AlInGaAs/GaAsP with opposite deformation in wells and barriers have been developed [6]. Despite the progress achieved in the study of the stressed superstructures, difficulties arise in the creation of heterostructures with optimal properties.…”

“…shows the experimental spectra for the Al 0.4 Ga 0 6. As/In 0.20 Al 0.19 Ga 0.48 As superstructure and the dependences of the quantum yield and degree of electron polarization on the energy of incident light photons calculated by Eqs.…”