Open AccessMie-type GaAs nanopillar array resonators for negative electron affinity photocathodes
Author(s) -
Xincun Peng,
M. Poelker,
Marcy Stutzman,
Bin Tang,
Shukui Zhang,
JiJun Zou
Publication year - 2020
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.378194
Subject(s) - nanopillar , photocathode , optoelectronics , materials science , quantum efficiency , optics , photoelectric effect , electron , resonance (particle physics) , nanophotonics , physics , nanotechnology , nanostructure , atomic physics , quantum mechanics
This paper presents modeling results of Mie-type GaAs nanopillar array resonant structures and the design of negative electron affinity photocathodes based on Spicer's three-step model. For direct-bandgap GaAs with high intrinsic absorption coefficient in the 500 ∼ 850 nm spectral range, photoelectrons were found to be highly localized inside the nanopillars near the top and side surfaces where electrons can be efficiently transported and emitted into vacuum, and the light reflectance can be reduced to ∼1% level at resonance wavelengths. Predictions of spectrally resolved photoemission indicate that these nanophotonics resonators, when properly optimized, can increase the photo-electron emission quantum efficiency at resonance wavelengths to levels limited only by the surface-electron escape probability, significantly outperforming traditional flat wafer photocathodes. Ultrafast photoelectric response is also expected from these nanostructured photocathodes due to the much shorter photoelectron transport distance in nanopillars compared to flat wafers. Given these unique optoelectronic properties, GaAs nanophotonic resonance structured photocathodes represent a very promising alternative to photocathodes with flat surfaces that are widely used in many applications today.