Theoretical analysis and modeling of photoemission characteristics of GaAs nanowire array photocathodes

Abstract

Gallium arsenide (GaAs) nanowire array (NWA) photocathodes have unique electrical and optical properties. Based on studies about photon absorption, band structure, and electron transport properties of GaAs nanowire, a photoemission model for GaAs NWA photocathodes is established. According to the model, we simulate and analyze the photocurrent, spectral response, and absorption properties of ordered GaAs NWA photocathodes. The results present a very interesting phenomenon; the photocurrent and spectral response peak at incident angles of 20°and 30°, respectively. These special properties of NWA cathodes differentiate them from their thin film counterparts. We also analyze the effects of nanowire length and diameter on the photocurrent of NWA cathodes, and find the optimum height of the nanowires is 10 μm. This study shows that NWAs exhibit higher absorbance and excellent charge transport. Thus, GaAs NWA photocathodes are excellent candidates for electron sources.

Negative electron affinity GaAs wire-array photocathodes

“…A theoretical treatment of a photoemission model based on ray-tracing techniques was adopted to calculate the spectral sensitivities of the GaAs wire-array photocathodes. The results revealed photocurrent and quantum efficiency (spectral response) peaks for the wirearray photocathodes with increasing incident angle [32]. The experimental results were in good agreement with the theoretical results.…”