3 August 2012 Self-limited ionization in bandgap renormalized GaAs at high femtosecond laser intensities
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Abstract
Theoretical modeling of photo-induced electron-hole plasma and bandgap dynamics in GaAs at high femtosecond laser intensities ( ∼ TW/cm2) employing a quantum kinetic formalism based on a generalized Boltzmann-type equation, predicts for the first time against expectations, the saturation of plasma densities despite the strong direct bandgap narrowing. Though the transient electronic bandgap renormalization provides a significant positive feedback for all relevant single-photon and impact ionization mechanisms, which is clearly observable at moderate (sub-TW/cm2) laser intensities, the counterintuitive plasma density saturation at higher laser intensities and high plasma densities ( ∼ 1022  cm−3) is dictated by much stronger negative feedback, originating from a highly-nonlinear transient enhancement of the corresponding Auger recombination coefficient for the shrinking bandgap. These theoretical predictions are in semi-quantitative agreement with the results of our time-resolved reflectivity infrared (IR)-pump experiments, which support this newly predicted process of self-limiting ionization dynamics in strongly photo-excited semiconductors, such as GaAs, with induced bandgap shrinkage.
© 2012 Society of Photo-Optical Instrumentation Engineers (SPIE)
Tzveta T. Apostolova, Andrey A. Ionin, Sergej Ivanovich Kudryashov, Leonid V. Seleznev, Dmitriy V. Sinitsyn, "Self-limited ionization in bandgap renormalized GaAs at high femtosecond laser intensities," Optical Engineering 51(12), 121808 (3 August 2012). https://doi.org/10.1117/1.OE.51.12.121808 . Submission:
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