【Others Papers】Intrinsic emittance properties of an Fe-doped β-Ga₂O₃(010) photocathode: Ultracold electron emission at 300 K and the polaron self-energy

      Researchers from the University of Illinois Chicago have published a dissertation titled "Intrinsic emittance properties of an Fe-doped β-Ga₂O₃(010) photocathode: Ultracold electron emission at 300 K and the polaron self-energy" in Journal of Applied Physics.

Abstract

      Measurements of the spectral emission properties of an iron-doped a β-Ga₂O₃(010) photocathode at 300 K reveal the presence of an ultracold contribution to the total electron beam emission with a 6 meV mean transverse energy (MTE) in the 3.5–4.4 eV photon energy range (282–354 nm). This extreme sub-thermal photoemission signal is consistent with direct emission of electrons photoexcited from the Fe dopant states into the low effective mass and positive electron affinity primary conduction band, and it is superimposed on a stronger signal with a larger MTE associated with an (optical)phonon-mediated momentum-resonant Franck–Condon (FC) emission process from a thermally populated and negative electron affinity upper conduction band. For photon energies above 4.5 eV, a transition from a long to a short transport regime is forced by an absorption depth reduction to below 100 nm and both MTE signals exhibit spectral trends consistent with phonon-mediated FC emission if the polaron formation self-energy is included in the temperature of the initial thermalized photoexcited electron distribution.

DOI：

https://doi.org/10.1063/5.0309595