Enhanced Optical Absorption and Spectral Photocurrent in a-Si:H by Single- and Double-Layer Silver Plasmonic Interfaces

Saleh, Zaki M.
NASSER, Hisham
ÖZKOL, Engin
Bek, Alpan
Turan, Raşit
Single and double plasmonic interfaces consisting of silver nanoparticles embedded in media with different dielectric constants including SiO2, SiNx, and Al:ZnO have been fabricated by a self-assembled dewetting technique and integrated to amorphous silicon films. Single plasmonic interfaces exhibit plasmonic resonances whose frequency is red-shifted with increasing particle size and with the thickness of a dielectric spacer layer. Double plasmonic interfaces consisting of two different particle sizes exhibit resonances consisting of double minima in the transmittance spectra. The optical extinction of a-Si:H deposited on these interfaces is broadened into the red indicating higher absorption and/or scattering at wavelengths higher than those typically absorbed by a-Si:H without plasmonic interfaces. While the photocurrent shows an overall decrease for the samples with the interfaces, significant enhancement of photocurrent is observed near the low-energy edge of the bandgap (600-700 nm). These results correlate well with the broadened extinction spectra of the interfaces and are interpreted in terms of enhanced absorption in that region.