Cathodo-luminescence spectroscopy is performed on silver and gold lamellar gratings of period 7.5 or 20 microns for a range of grating amplitudes from 0.1 to 4.6 microns. The overall emission spectrum consists of a 400 nm wide band centered at ~600 nm which depends little on the grating amplitude, metal, or e-beam energy. For the larger grating amplitudes the emission spectrum is periodically modulated as a function of wavelength. Both the strength of the emission envelop and the depth and phase of the modulation depend on grating orientation with respect to the light collection axis, the distance of the excitation spot from the grating, and the distance between the grating and the collection optics. The modulation can be explained as interference of surface emission from grating bars and grooves. The origin of the emission remains unclear, as mechanisms of electron collision with image charge, transition radiation, surface contamination, and inverse photo-electron effect all fail to explain the observed spectrum. This work is relevant to the interpretation of cathodoluminescence studies of surface plasmons on structured metals for nano-photonic applications.

Date Published: 13 May 2011
PDF: 9 pages
Proc. SPIE 8031, Micro- and Nanotechnology Sensors, Systems, and Applications III, 80312V (13 May 2011); doi: 10.1117/12.884162

Published in SPIE Proceedings Vol. 8031:
Micro- and Nanotechnology Sensors, Systems, and Applications III
Thomas George; M. Saif Islam; Achyut K. Dutta, Editor(s)