For the experiment, the researchers built nanowire semiconductors with an organic material. They use a technique called high-vacuum organic molecular beam deposition to spread organic and metal layers – including gold – on gallium nitride nanorods.
Once the sample was prepared, it was subjected to pulses of laser light to excite the excitons that potentially serve as an energy pump to guide plasmon waves over the gold-coated metal film without losing power.
The use of organic film is unique to the UC experiment, according to associate professor Hans-Peter Wagner. The film works as a spacer to control the energy flow between excitons in the nanowire and the oscillation of metal plasmons.
They then measured the resulting luminescence of the nanowire to observe how light couples to the metal film.
"The luminescence is our interest. So we coat them and see: How does the photoluminescence characteristic change?" UC graduate student Fatemesadat Mohammadi said.
The UC project used a gold coating so that experiments could be replicated at a later date without risk of oxidation. But traditional coatings such as silver, Mohammadi said, hold even more promise.