Interplay between direct gap renormalization and intervalley scattering in AlxGa1−xAs near the Γ–X crossover

Andrade, L. H. F.; Marotti, Ricardo E.; Quivy, A. A.; Cruz, Carlos Henrique de Brito

doi:10.1016/s0038-1098(01)00480-x

Cited by 1 publication

(1 citation statement)

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“…Following the intervalley scattering investigations performed in GaAs and other semiconductors using the picosecond and femtosecond optical spectroscopic techniques, [6][7][8][9][10][11][12][13][14] there are two main ways for initiating intervalley transitions in time-resolved experiments. One method is to excite electrons from the bottom of the conduction ⌫ band to upper energy states with below-band-gap infrared femtosecond op-tical pulses via free-carrier absorption and use the aboveband-gap UV femtosecond probe beam to monitor changes in electron cooling behavior with and without the intervalley scattering.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved intervalley transitions in GaN single crystals

Geiser

Jun

et al. 2007

Journal of Applied Physics

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Articles you may be interested inTime-resolved femtosecond optical characterization of multi-photon absorption in high-pressure-grown Al0.86Ga0.14N single crystals Growth and deep ultraviolet picosecond time-resolved photoluminescence studies of AlN/GaN multiple quantum wells Appl. Phys. Lett. 78, 3690 (2001); 10.1063/1.1377317 Time-resolved Raman studies of the decay of the longitudinal optical phonons in wurtzite GaNWe present a direct observation of time-resolved intervalley transitions of electrons between the conduction band ⌫ and L valleys in GaN single crystals using a two-color ͑ultraviolet and near-infrared͒, femtosecond, pump-probe spectroscopic technique. We have found that the threshold for the ⌫ ↔ L transition appears at the energy of 4.51± 0.05 eV and the electron scattering time from the ⌫ to L valley is comparable to the 170 fs width of our pump pulses, while the return process of electrons from L to ⌫ is measurably slower. The L to ⌫ scattering time is 1.02 ps, while the total depopulation time of the L valley is estimated to be ϳ20 ps. Our physical model, based on the three-state rate equations, fitted our experimental data very well and allowed us to calculate the optical phonon emission time of 290 fs. The deformation potential between the two valleys was also obtained from the intervalley scattering modeling and the value was 0.92ϫ 10 9 eV/ cm.

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