Spectral dependence of light output from LEIT devices on electrode morphology

Abstract
The light output from Al-I-Au tunnel junctions is observed to depend on the morphology of the Au film electrode. Films deposited quickly (2 nm s-1) give out less light, especially towards the blue end of the spectrum, than those deposited slowly (0.03 nm s-1). An explanations is offered in terms of elastic scattering of surface plasmon polaritons in the Au film. The scattering increases the chance of plasmon decay by internal electromagnetic absorption at the expanse of photon emission. A model, of more general applicability, has been developed which can explain the results. SEM has been used to determine the grain size in the Au films and STM to measure the surface roughness.