Direct imaging of electron recombination and transport on a semiconductor surface by femtosecond time-resolved photoemission electron microscopy

Abstract

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Femtosecond time-resolved photoemission electron microscopy operated at sample illumination from the rear side

“…[8][9][10] The technique attracted additional interest in the study of carrier transport and recombination in semiconductors. 11,12 Important technological advancements of the technique include the addition of interferometric time resolution, 8 the implementation of energy resolving detection schemes, 13 and the operation at laser illumination in normal incidence as opposed to the standard oblique incidence geometry. 4 In normal incidence 2PPEEM (NI2PPEEM), the symmetry of the studied problem is not affected by the direction of incidence of the excitation laser.…”

Pulling apart photoexcited electrons by photoinducing an in-plane surface electric field

“…As a result, SUEM has recently observed anomalous and anisotropic diffusion phenomena in amorphous silicon ( 2 ) and black phosphorous ( 8 ), respectively. In contrast, time-resolved photoemission electron microscopy (TR-PEEM) techniques ( 9 ) combine the high temporal resolution provided by ultrafast optical pulses with the high spatial resolution provided by photoemitted electrons to study dynamics in metals ( 10 , 11 ) and semiconductors ( 12 , 13 ). In semiconductors, TR-PEEM can directly image the density of photoexcited electrons as they evolve in space and time, as exemplified by our recent observation of the motion of electrons in a type II semiconductor heterostructure ( 14 ).…”

Observing charge separation in nanoantennas via ultrafast point-projection electron microscopy

“…More specifically, point-projection microscopes feature shorter propagation distances than conventional electron microscopes but are currently still limited to time resolutions of 100 fs or more by dispersion 11 , 29 . Fs-photoelectron emission microscopy (PEEM) has been successfully used to image local electric fields at surfaces with few tens of fs and few tens of nm resolution 27 , 30 , 31 and can probe the dynamics of, e.g., plasmons 32 or excitons 33 in nanostructures. Generally, PEEM probes how photoelectrons are released from a nanostructure by transient local electric fields.…”