High Spin Polarization of Conduction Band Electrons in GaAs-GaAsP Strained Layer Superlattice Fabricated as a Spin-Polarized Electron Source

Abstract

We measured a spin-dependent luminescence from a GaAs–GaAsP strained layer superlattice and GaAs substrate to evaluate the spin polarization of conduction band electrons excited by circularly polarized light. The GaAs–GaAsP strained layer superlattice with a mixture of group-V elements, As and P, was considered as a suitable spin-polarized electron source because the discrepancy of the valence band was reported to be larger than that of the conduction band. The observed maximum circular polarizations of the luminescence from the GaAs–GaAsP strained layer superlattice and GaAs substrate were 68% and 15%, respectively. The dependence of the circular polarization of the luminescence on the excitation photon energy was well explained by the calculated band structure. The initial spin polarizations of conduction band electrons excited in the GaAs–GaAsP strained layer superlattice and GaAs substrate were estimated to be 95% and 46%, respectively, from the luminescence polarization, lifetime and spin relaxation time. The high initial spin polarization of conduction band electrons proved the high performance of a photocathode with the GaAs–GaAsP strained layer superlattice as the spin-polarized electron source.

High-Performance Spin-Polarized Photocathodes Using a GaAs/GaAsP Strain-Compensated Superlattice

“…These times were determined for GaAs/GaAsP strained SL structures using timeresolved spin-dependent luminescence measurements. 13) The lifetime and spin-relaxation time of conduction band electrons in a 100-nm-thick GaAs/GaAsP strained SL layer were determined to be 55 AE 3 and 140 AE 12 ps, respectively. This means that the QE will reach its maximum before the spin polarization begins to decrease rapidly with increasing SL layer thickness.…”

Photoionization Characteristics of Sr into 5skl Continua through the Spin-Resolved Ion Detection by Laser-Induced Fluorescence

“…1) For instance, the development of a spin-polarized electron beam is inevitable for parity violation experiments and nucleon spin structure studies in highenergy physics, 2,3) whereas manipulating electron spin in semiconductor devices has become important under the concept of ''spintronics''. 4,5) In particular, the control of electron spin and nuclear spin in semiconductor materials is a key step towards quantum computing. [6][7][8] Being supported by demands in various fields, spin-polarized electron sources have been developed for decades, most commonly by irradiating GaAs crystals using a circularly polarized laser.…”

“…Owing to the further development of this technique, such as using GaAs/GaAsP superlattice, it is not difficult nowadays to polarize electrons over 85%. [2][3][4] However, continuous irradiation using a strong laser onto a solid state target would cause damage after some period of time, resulting in the deterioration of polarization and yield. One possible way out of this problem is to use a gas target instead of a solid one.…”