Spin and energy relaxation in germanium studied by spin-polarized direct-gap photoluminescence

Abstract

Spin orientation of photoexcited carriers and their energy relaxation is investigated in bulk Ge by studying spin-polarized recombination across the direct band gap. The control over parameters such as doping and lattice temperature is shown to yield high polarization degree, namely larger than 40%, as well as a fine-tuning of the angular momentum of the emitted light with a complete reversal between right- and left-handed circular polarization. By combining the measurement of the optical polarization state of band-edge luminescence and Monte Carlo simulations of carrier dynamics, we show that these very rich and complex phenomena are the result of the electron thermalization and cooling in the multi-valley conduction band of Ge. The circular polarization of the direct-gap radiative recombination is indeed affected by energy relaxation of hot electrons via the X valleys and the Coulomb interaction with extrinsic carriers. Finally, thermal activation of unpolarized L valley electrons accounts for the luminescence depolarization in the high temperature regime.

References in corpus (3)

• Electronic measurement and control of spin transport in Silicon
• Intrinsic Spin Lifetime of Conduction Electrons in Germanium
• Spin-dependent optical properties in strained silicon and germanium

Cited by in corpus (15)

• Polarization analysis of excitons in monolayer and bilayer transition-metal dichalcogenides
• Temperature-dependent photoluminescence characteristics of GeSn epitaxial layers
• Exciton valley depolarization in monolayer transition-metal dichalcogenides
• Giant g factor tuning of long-lived electron spins in Ge
• Carrier and Spin Coherent Dynamics in Strained Germanium-Tin Semiconductor on Silicon
• Temperature-dependent photoluminescence in Ge: experiment and theory
• Disentangling nonradiative recombination processes in Ge micro-crystals on Si substrates
• Optical orientation of electron spins and valence band spectroscopy in germanium
• Magneto-optical determination of the carrier lifetime in coherent Ge(1-x)Sn(x)/Ge heterostructures
• Spin-dependent direct gap emission in tensile-strained Ge films on Si substrates
• Optical spin orientation and depolarization in Ge
• Optical spin orientation of minority holes in a modulation-doped GaAs/(Ga,Al)As quantum well
• Hot-electron effect in spin relaxation of electrically injected electrons in intrinsic Germanium
• Optical manipulation of the Rashba effect in germanium quantum wells
• Optical spin pumping in silicon