Dependence of electron emission current density on excitation power density from Cs/O-activated negative electron affinity InGaN photocathode

The dependence of the electron emission current density on the excitation power density of a Cs/O-activated negative electron affinity (NEA) InGaN photocathode was investigated. The emission current density of the NEA-InGaN photocathode increased monotonically with the excitation power density in the measured range. The emission current density reached 5.6 × 103 A/cm2 at an excitation power density of 2.6 × 106 W/cm2. Using the electron thermal energy estimated by comparing simulation and experimental results [D. Sato, H. Shikano, A. Koizumi, T. Nishitani, Y. Honda, and H. Amano, J. Vac. Sci. Technol. B 39, 062209 (2021)], the reduced brightness of 4 × 108 A/m2 sr V was derived.