Ultraviolet surface plasmon-mediated low temperature hydrazine decomposition
Siying Peng, Matthew T. Sheldon, Wei-Guang Liu, Andrés Jaramillo-Botero, William A. Goddard III, Harry A. Atwater
Abstract
Conventional methods require elevated temperatures in order to dissociate high-energy nitrogen bonds in precursor molecules such as ammonia or hydrazine used for nitride film growth. We report enhanced photodissociation of surface-absorbed hydrazine (N_2H_4) molecules at low temperature by using ultraviolet surface plasmons to concentrate the exciting radiation. Plasmonic nanostructured aluminum substrates were designed to provide resonant near field concentration at λ = 248 nm (5 eV), corresponding to the maximum optical cross section for hydrogen abstraction from N_2H_4. We employed nanoimprint lithography to fabricate 1 mm × 1 mm arrays of the resonant plasmonic structures, and ultraviolet reflectance spectroscopy confirmed resonant extinction at 248 nm. Hydrazine was cryogenically adsorbed to the plasmonic substrate in a low-pressure ambient, and 5 eV surface plasmons were resonantly excited using a pulsed KrF laser. Mass spectrometry was used to characterize the photodissociation products and indicated a 6.2× overall enhancement in photodissociation yield for hydrazine adsorbed on plasmonic substrates compared with control substrates. The ultraviolet surface plasmon enhanced photodissociation demonstrated here may provide a valuable method to generate reactive precursors for deposition of nitride thin film materials at low temperatures.
Group Members
Peng, S., Sheldon, M. T., Liu, W., Jaramillo-Botero, A., III, W. A. G., & Atwater, H. A. (2015). Ultraviolet surface plasmon-mediated low temperature hydrazine decomposition. *Applied Physics Letters*, *106*(2), Art. No. 023102. https://doi.org/10.1063/1.4905593