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Ultrafast Photoionization and Energy Absorption in Bulk Silicon and Germanium

Authors:
Tzveta Apostolova
Boyan Obreshkov

Keywords: group IV semiconductors, femtosecond laser irradiation, nonthermal melting, nonlinear optical properties, multiphoton and tunnel ionization

Abstract:
The deposited energy and the transient electron density in the bulk of silicon and germanium, irradiated by intense 30 fs pulsed laser with near-infrared and mid-infrared wavelengths (800nm-5μm) and intensities (1GW/cm2-1TW/cm2) are obtained by solving the time-dependent Schrodinger equation in single active electron approximation. The microscopic electronic response associated with the generation of photoelectrons and ultrafast macroscopic photocurrents inside the bulk of the materials are presented. Wavelength dependent coefficients for multi-photon absorption are determined for each material. Dielectric breakdown thresholds are obtained by comparison to energy required to cause melting or sublimation of the solid. For laser intensities below the damage threshold, the cycle-resolved photo-ionization exhibits transient oscillatory dynamics of electron-hole pairs. These non-linear oscillations of the electron density result in a sub-cycle modulation of optical properties and high-harmonic generation.

Pages: 17 to 22

Copyright: Copyright (c) IARIA, 2018

Publication date: September 16, 2018

Published in: conference

ISSN: 2308-3530

ISBN: 978-1-61208-665-1

Location: Venice, Italy

Dates: from September 16, 2018 to September 20, 2018