title: Direct Time-Domain View of Auger Recombination in a Semiconductor.
abstract: The radiationless recombination of electron-hole pairs in semiconductors is detrimental to optoelectronic technologies. A prominent mechanism is Auger recombination, in which nonradiative recombination occurs efficiently by transferring the released energy-momentum to a third charge carrier. Here we use femtosecond photoemission to directly detect Auger electrons as they scatter into energy and momentum spaces from Auger recombination in a model semiconductor, GaSb. The Auger rate is modulated by a coherent phonon mode at 2 THz, confirming phonon participation in momentum conservation. The commonly assumed Auger rate constant is found not to be a constant, but rather decreases by 4 orders of magnitude as hot electrons cool down by ∼90  meV. These findings provide quantitative guidance in understanding Auger recombination and in designing materials for efficient optoelectronics.
authors.affiliation: Department of Chemistry, Columbia University, New York, New York 10027, USA.
authors.forename: Kristopher W
authors.initials: KW
authors.lastname: Williams
authors.affiliation: Department of Chemistry, Columbia University, New York, New York 10027, USA.
authors.forename: Nicholas R
authors.initials: NR
authors.lastname: Monahan
authors.affiliation: Department of Chemistry, Columbia University, New York, New York 10027, USA.
authors.forename: Tyler J S
authors.initials: TJ
authors.lastname: Evans
authors.affiliation: Department of Chemistry, Columbia University, New York, New York 10027, USA.
authors.forename: X-Y
authors.initials: XY
authors.lastname: Zhu