Meta-surface negative electron affinity photocathode

What is it about?

Gallium arsenide (GaAs)-based negative electron affinity (NEA) photocathodes (PCs) have garnered significant interest for use in spin- polarized electron sources and low-light-level imaging systems. Progress in these applications requires PCs with high quantum efficiency (QE) and fast response times. In this work, the all-dielectric meta-surfaces were used as the light manager to improve the photoemission performance of the ultra-thin GaAs NEA-PCs.

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Photo by John Adams on Unsplash

Photo by John Adams on Unsplash

Why is it important?

QE of
40% has been reported for the t-mode thick ( aAs NEA-PCs. Nevertheless, practical applications of these devices have been seriously restricted by their long response time (tens of picoseconds). In this work, the all-dielectric meta-surfaces (ADMS) were designed as the light managers for the t-mode ultra-thin GaAs NEA-PCs. For the 500–850 nm waveband, high light absorption can be obtained through coupling the electromagnetic dipole moments of ADMS into the leaky optical modes in ultra-thin GaAs NEA-PC layer, which leads to enhanced QE higher than that of the thick ones, the response time less than 5 ps, and the mean transverse energy less than 60 meV, respectively.