Regensburg 2010 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 49: Optical Properties
HL 49.2: Talk
Thursday, March 25, 2010, 09:45–10:00, H14
Finite-difference time-domain simulations of fabricated black silicon nanostructures: Optimal geometries for an antireflective coating — Adam Williamson1,2 and •Andreas Voerckel1 — 1X-FAB Semiconductor Foundries AG, Haarbergstrasse 67 99097 Erfurt, Germany — 2Technische Universität Ilmenau, Gustav-Kirchhoff-Str. 7, 98693 Ilmenau, Germany
Nano-structured silicon has received a growing and serious amount of interest in industrial technology and university research, particularly in regard to the possibility of such nanostructures in optics, with the primary interest here being black silicon as an anti-reflective coating (ARC) for photodiodes. Current literature now contains a wealth of morphological information to influence structure growth and shape in fluorine-based plasma etching in the presence of oxide-forming or fluorocarbon gas inhibitors [1, 2]. Using the computationally efficient grid-based differential time-domain numerical modeling of the finite-difference time-domain (FDTD) method, approximations to Maxwell’s equations are solved to model the optical properties of crystalline black silicon. Multiple geometries, from pillars to more pyramid and needle-like structures, are considered and results are correlated to actual scanning electron microscope (SEM) pictures with corresponding reflection measurements taken in a Cary 5000 UV*VIS spectrophotometer with accompanying integrating (Ulbricht) sphere from 200nm to 800nm to evaluate both diffuse and specular reflection from the silicon surface. Optimal geometries are simulated and the consequences for photodiode applications are discussed.