Showing papers by "Tsing-Hua Her published in 1998"

Microstructuring of silicon with femtosecond laser pulses

Abstract: We report that silicon surfaces develop an array of sharp conical spikes when irradiated with 500 laser pulses of 100-fs duration, 10-kJ/m2 fluence in 500-Torr SF6 or Cl2. The spikes are up to 40-μm tall, and taper to about 1-μm diam at the tip. Irradiation of silicon surfaces in N2, Ne, or vacuum creates structured surfaces, but does not create sharp conical spikes.

Surface femtochemistry of CO/O2/Pt(111): The importance of nonthermalized substrate electrons

Abstract: We studied the surface femtochemistry of CO/O2/Pt(111) induced with 0.3 ps laser pulses over a wide range of wavelength and fluence. Below 10 μJ/mm2, the yields depend linearly on fluence. Above 10 μJ/mm2, the yields scale nonlinearly in the fluence. From the dependence of the yields on wavelength, we determine that the nonlinear surface femtochemistry is influenced by nonthermal substrate electrons.

Novel conical microstructures created in silicon with femtosecond laser pulses

Abstract: Summary form only given. Silicon wafers are mounted inside a vacuum chamber backfilled with gas and then irradiated with 800-nm pulses from a regeneratively amplified Ti:sapphire laser. Following laser treatment, the samples are removed from the chamber and analyzed with a scanning electron microscope (SEM).

Black silicon: A new light absorber for photovoltaic applications

Abstract: Intensive research efforts have been conducted to increase the conversion efficiency of solar cells and optical detection devices by reducing reflection and enhancing optical absorption.