DYNAMICS OF ELECTRIC-FIELD SCREENING IN A BULK GAAS MODULATOR

[摘要] The transient development of electric-field distributions in a biased GaAs film after low density optical excitation is determined by measurements of Franz-Keldysh modulations with a time resolution of 100 fs. The experimental results are compared with theoretical calculations. The transient field is calculated with a drift-diffusion model. Our calculation of the dielectric function of GaAs includes the Coulomb coupling and the electric field. The resulting optical transmission changes are calculated with a transfer-matrix method. The theory predicts a modification of the Franz-Keldysh modulation due to the nonuniform field, in quantitative agreement with the experimental observations.

[关键词] BAND-EDGE;ELECTROABSORPTION;PHOTOREFLECTANCE;SEMICONDUCTORS