Superluminescence from an optically pumped molecular tunneling junction by
injection of plasmon induced hot electrons
#MMPMID26171286
Braun K
; Wang X
; Kern AM
; Adler H
; Peisert H
; Chassé T
; Zhang D
; Meixner AJ
Beilstein J Nanotechnol
2015[]; 6
(?): 1100-6
PMID26171286
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Here, we demonstrate a bias-driven superluminescent point light-source based on
an optically pumped molecular junction (gold substrate/self-assembled molecular
monolayer/gold tip) of a scanning tunneling microscope, operating at ambient
conditions and providing almost three orders of magnitude higher
electron-to-photon conversion efficiency than electroluminescence induced by
inelastic tunneling without optical pumping. A positive, steadily increasing bias
voltage induces a step-like rise of the Stokes shifted optical signal emitted
from the junction. This emission is strongly attenuated by reversing the applied
bias voltage. At high bias voltage, the emission intensity depends non-linearly
on the optical pump power. The enhanced emission can be modelled by rate
equations taking into account hole injection from the tip (anode) into the
highest occupied orbital of the closest substrate-bound molecule (lower level)
and radiative recombination with an electron from above the Fermi level (upper
level), hence feeding photons back by stimulated emission resonant with the gap
mode. The system reflects many essential features of a superluminescent light
emitting diode.
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