title: Direct observation of phonon emission from hot electrons: spectral features in diamond secondary electron emission.
abstract: In this work we use high-resolution synchrotron-based photoelectron spectroscopy to investigate the low kinetic energy electron emission from two negative electron affinity surfaces of diamond, namely hydrogenated and lithiated diamond. For hydrogen-terminated diamond electron emission below the conduction band minimum (CBM) is clearly observed as a result of phonon emission subsequent to carrier thermalization at the CBM. In the case of lithiated diamond, we find the normal conduction band minimum emission peak is asymmetrically broadened to higher kinetic energies and argue the broadening is a result of ballistic emission from carriers thermalized to the CBM in the bulk well before the onset of band-bending. In both cases the spectra display intensity modulations that are the signature of optical phonon emission as the main mechanism for carrier relaxation. To our knowledge, these measurements represent the first direct observation of hot carrier energy loss via photoemission.
authors.affiliation: Department of Imaging and Applied Physics, Curtin University, Bentley WA 6102 Australia.
authors.forename: Kane M
authors.initials: KM
authors.lastname: O'Donnell
authors.forename: Mark T
authors.initials: MT
authors.lastname: Edmonds
authors.forename: Jürgen
authors.initials: J
authors.lastname: Ristein
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Rietwyk
authors.forename: Anton
authors.initials: A
authors.lastname: Tadich
authors.forename: Lars
authors.initials: L
authors.lastname: Thomsen
authors.forename: Christopher I
authors.initials: CI
authors.lastname: Pakes
authors.forename: Lothar
authors.initials: L
authors.lastname: Ley