Jinjuan Du

The AlGaN photocathode with a superlattice emission layer was grown by metal organic chemical vapor deposition. The existence of the superlattice structure was confirmed using a transmission electron microscope, and its optical and electrical properties were measured. The results showed that the introduction of a superlattice emission layer can reduce the transmittance and reflectance at 275 nm and improve the absorption of incident light. In particular, the Hall measurement results indicate that the introduction of a superlattice structure can significantly increase the concentration of holes in the AlGaN photocathode material. The activation experiment demonstrated that the photocurrent of the AlGaN photocathode subassembly with a superlattice structure increased significantly after Cs/O activation and that it showed better photoemission performance. The increase in the incident light absorption to produce more photoelectrons, the enhancement of photoelectron transport capacity by the polarized electric field generated by the superlattice structure, and the reduction in the surface barrier caused by the higher hole concentration were responsible for the significant improvement in photoemission performance.

C-doped GaAs is considered a potential material for negative electron affinity photocathodes, where the p-type doped property is beneficial to photoemission. To clarify the stability and efficiency during Cs/O activation, the gradient concentration of Cs adsorption and Cs/O co-adsorption models of C-doped GaAs are established. The work function, adsorption energy, and surface dipole moment are intensified by first principles calculation based on density functional theory. Experimental results demonstrate that Cs/O activation effectively enhances the performance of C-doped GaAs photocathodes, resulting in high levels of quantum efficiency. Therefore, we conclude that C-doped GaAs photocathodes have the potential to significantly improve the photoelectric emission performance and stability of GaAs photocathodes, making them a viable candidate for future applications.

SPIE Digital Library Proceedings

The InGaN/AlGaN multiquantum‐well microrod‐array structure is grown on c‐plane GaN template with SiO₂ microholes patterned as a mask. The surface morphology exhibits the accurately ordered microrod‐array structure. Temperature‐dependent photoluminescence (PL) measurement indicates that the PL peaks redshift as the temperature increases. Room‐temperature PL and cathode luminescence spectra show that the different positions on InGaN/AlGaN microrod arrays have different luminous peaks. The successful fabrication of InGaN/AlGaN microrod arrays is of great significance for the realization of multicolor emission and the design of new optoelectronic devices.