Low-temperature positron transport in semi-insulating GaAs

[摘要] Positron diffusion and drift in semi-insulating (SI) GaAs in the temperature range of 50-309 K were studied by the slow-positron beam technique. Both the temperature-dependent positron diffusion coefficient and positron mobility were measured independently using the method reported recently [Y. Y. Shan et al., Phys. Rev. B 54, 1982 (1996)]. The experimental results are consistent with the Einstein relation. The diffusion coefficient and mobility approximately follow D+(T) = 9400T(-beta) cm(2) s(-1), and mu(+)(T) = 10(8) x T-sigma cm(2) V-1 s(-1), with beta = 1.5+/-0.1, and sigma = 2.5+/-0.2, respectively in the temperature range of 50-300 K. The results are consistent with scattering from optical-phonon modes as the dominant scattering process for positron transport in GaAs (SI) in this temperature range. No trapped positron states were observed to 50 K.

[关键词] MONTE-CARLO CALCULATIONS;MONOENERGETIC POSITRONS;KEV ELECTRON;DIFFUSION;SURFACES;MOBILITY;SI;INTERFACE;SOLIDS;ANNIHILATION