Modelling Photocathode Performance using Density Functional Theory

The structure and composition of a crystalline material can strongly affect electronic properties such as the electron affinity and the work function. By optimising the properties of the material, it is possible to design photocathodes for a wide range of applications. Molecular beam epitaxy (MBE) provides much improved control over the composition and synthesis of a photocathode versus traditional manufacturing methods. In this paper, we verify the application and reliability of density functional theory (DFT) to model photocathode performance by comparing simulations of dicaesium telluride- and gallium arsenide-like structures to other simulated and experimental results. DFT modelling was carried out using MEDEA-VASP software, with verification achieved for simulations of the band structure and density of states. This enables ongoing simulations to optimise photocathode materials with regards to properties including electron affinity and absorption coefficient.