PbTe(111) Sub-Thermionic Photocathode: A Route to High-Quality Electron Pulses

The emission properties of PbTe(111) single crystal have been extensively investigated to demonstrate that PbTe(111) is a promising low root mean square transverse momentum ({\Delta}p${}_T$) and high brightness photocathode. The density functional theory (DFT) based photoemission analysis successfully elucidates that the ‘hole-like’ {\Lambda}${}_6^{+}$ energy band in the $L$ valley with low effective mass $m^{\ast }$ results in low {\Delta}p${}_T$. Especially, as a 300K solid planar photocathode, Te-terminated PbTe(111) single crystal is expected to be a potential 50K electron source.