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

TLDR

Techniques to probe carrier dynamics, which govern many semiconductor device characteristics, have been extensively developed. The study reports direct imaging of electron dynamics on semiconductor surfaces using time‑resolved photoemission electron microscopy with femtosecond laser pulses. The method employed a variable‑repetition‑rate femtosecond laser system to suppress charging and time‑resolved photoemission electron microscopy to image electron dynamics. The recombination of photogenerated electrons and their lateral drift under an external electric field on a GaAs surface were visualized, and mobility was estimated from a linear drift‑velocity versus potential‑gradient relationship.

Abstract

Much effort has been devoted to the development of techniques to probe carrier dynamics, which govern many semiconductor device characteristics. We report direct imaging of electron dynamics on semiconductor surfaces by time-resolved photoemission electron microscopy using femtosecond laser pulses. The experiments utilized a variable-repetition-rate femtosecond laser system to suppress sample charging problems. The recombination of photogenerated electrons and the lateral motion of the electrons driven by an external electric field on a GaAs surface were visualized. The mobility was estimated from a linear relationship between the drift velocity and the potential gradient.