Modeling Photocathode Performance Using MedeA-VASP Simulation Software

• Published in: IEEE transactions on nuclear science Vol. 67; no. 9; pp. 1987 - 1992
• Main Authors: Williams, Jamie O. D., Lapington, Jon S., Campion, Richard, Foxon, Tom, Temperton, Robert H., O'Shea, James N.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-09-2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Absorption; Absorptivity; Affinity; Cathodes; Composition; Computer programs; Computer simulation; Crystal structure; Crystallinity; Density functional theory; Density functional theory (DFT); Electron affinity; Electron optics; Gallium; Gallium arsenide; modeling; Molecular beam epitaxial growth; Molecular beam epitaxy; Optical properties; Parameter identification; photocathode; Photocathodes; Photonic band gap; Photonics; Production methods; quantum efficiency (QE); Software; Stoichiometry; Tellurides; Work functions
• ISSN: 0018-9499; 1558-1578
• DOI: 10.1109/TNS.2020.3011355

Photocathodes have a wide range of applications, and different materials can be used depending on the incident photon wavelength. The structure and composition of a crystalline material can strongly affect the electronic properties such as the electron affinity and the work function. Molecular beam epitaxy (MBE) provides much improved control over the composition and synthesis of a photocathode versus traditional manufacturing methods, which allows these electrical and optical properties to be optimized for a particular application. In this article, we use density functional theory (DFT) through commercially available MedeA-VASP simulation software to identify the available parameter space of electron affinity and absorption coefficient by varying the stoichiometry and crystallinity. We identify trends to motivate the manufacture of new dicesium telluride- and gallium arsenide-like materials via MBE to optimize photocathode performance for a particular application.