Document Type

Article

Publication Date

2023

DOI

10.1063/5.0130884

Publication Title

Journal of Applied Physics

Volume

133

Issue

2

Pages

023105 (1-13)

Abstract

Nanostructured negative electron affinity GaAs photocathodes for a polarized electron source are studied using finite difference time domain optical simulation. The structures studied are nanosquare columns, truncated nanocones, and truncated nanopyramids. Mie-type resonances in the 700–800 nm waveband, suitable for generation of polarized electrons, are identified. At resonance wavelengths, the nanostructures can absorb up to 99% of the incident light. For nanosquare columns and truncated nanocones, the maximum quantum efficiency (QE) at 780 nm obtained from simulation is 27%, whereas for simulated nanopyramids, the QE is ∼21%. The high photocathode quantum efficiency is due to the shift of Mie resonance toward the longer wavelength, leading to increased light absorption. The field profile distribution shows the excitation of dipole and quadrupole modes within the nanostructures at resonant frequencies. This leads to enhanced photoabsorption and photoelectron generation closer to emission surfaces than for a flat photocathode. The enhanced photoabsorption and reduced electron transport distance for the nanostructured photocathode enhance its QE compared to that for the flat surface wafer.

Rights

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in

Rahman, M. A. A., Zhang, S., & Elsayed-Ali, H. E. (2023). Quantum efficiency enhancement in simulated nanostructured negative electron affinity GaAs photocathodes. Journal of Applied Physics, 133(2), 1-13, Article 023105.

and may be found at https://doi.org/10.1063/5.0130884.

Data Availability

Article states: "The data that support the findings of this study are available from the corresponding author upon reasonable request."

Comments

Included after a 12 month embargo in accordance with publisher policy.

Original Publication Citation

Rahman, M. A. A., Zhang, S., & Elsayed-Ali, H. E. (2023). Quantum efficiency enhancement in simulated nanostructured negative electron affinity GaAs photocathodes. Journal of Applied Physics, 133(2), 1-13, Article 023105. https://doi.org/10.1063/5.0130884

ORCID

0000-0002-8348-5204 (Rahman)

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