Bias-dependent electron spin lifetimes in n-GaAs and the role of donor impact ionization

• Published in: Applied physics letters Vol. 89; no. 10
• Main Authors: Furis, M., Smith, D. L., Crooker, S. A., Reno, J. L.
• Format: Journal Article
• Language: English
• Published: 04.09.2006
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.2345608

In bulk n-GaAs epilayers doped near the metal-insulator transition, the authors study the evolution of electron spin lifetime τs as a function of applied lateral electrical bias Ex. τs is measured via the Hanle effect using magneto-optical Kerr rotation. At low temperatures (T<10K, where electrons are partially localized and τs>100ns at zero bias), a marked collapse of τs is observed when Ex exceeds the donor impact ionization threshold at ∼10V∕cm. A steep increase in the concentration of warm delocalized electrons—subject to Dyakonov-Perel spin relaxation [Sov. Phys. Solid State 13, 3023 (1972)]—accounts for the rapid collapse of τs and strongly influences electron spin transport in this regime.