Photo-assisted Ultrafast Scanning Electron Microscopy (USEM) maps the dynamics of surface photovoltages and local electric fields in semiconducting samples. Photovoltages and their gradients close to surface affect the emission yield and the detection efficiency of secondary electrons (SE), leading to photoexcited SE 2D patterns. In this work, we present a method to characterize the evolution of the patterns up to ultrafast regime. These results reveal the role of surface states in affecting the external field dynamics at picoseconds. Moreover, we show that tiny changes in surface preparation express deeply different photoexcited voltage signals. We investigate the relation between the surface chemistry of Si and photo-induced SE contrast.

Dynamical imaging of local photovoltage at semiconductor surface by photo-assisted ultrafast scanning electron microscopy

Mohamed Zaghloul;Silvia M. Pietralunga;Gabriele Irde;Vittorio Sala;Giulio Cerullo;Hao Chen;Giovanni Isella;Guglielmo Lanzani;Maurizio Zani;Alberto Tagliaferri
2021-01-01

Abstract

Photo-assisted Ultrafast Scanning Electron Microscopy (USEM) maps the dynamics of surface photovoltages and local electric fields in semiconducting samples. Photovoltages and their gradients close to surface affect the emission yield and the detection efficiency of secondary electrons (SE), leading to photoexcited SE 2D patterns. In this work, we present a method to characterize the evolution of the patterns up to ultrafast regime. These results reveal the role of surface states in affecting the external field dynamics at picoseconds. Moreover, we show that tiny changes in surface preparation express deeply different photoexcited voltage signals. We investigate the relation between the surface chemistry of Si and photo-induced SE contrast.
EPJ Web of Conferences
File in questo prodotto:
File Dimensione Formato  
epjconf_eosam2021_11001.pdf

accesso aperto

: Publisher’s version
Dimensione 2.73 MB
Formato Adobe PDF
2.73 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1191150
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact