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arXiv · 2109.05241

Hot electron cooling in InSb probed by ultrafast time-resolved terahertz cyclotron resonance

Chelsea Q. Xia·Maurizio Monti·Jessica L. Boland·Laura M. Herz·James Lloyd-Hughes·Marina R. Filip·Michael B. Johnston
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Abstract

Measuring terahertz (THz) conductivity on an ultrafast time scale is an excellent way to observe charge-carrier dynamics in semiconductors as a function of time after photoexcitation. However, a conductivity measurement alone cannot separate the effects of charge-carrier recombination from effective mass changes as charges cool and experience different regions of the electronic band structure. Here we present a form of time-resolved magneto-THz spectroscopy which allows us to measure cyclotron effective mass on a picosecond time scale. We demonstrate this technique by observing electron cooling in the technologically-significant narrow-bandgap semiconductor indium antimonide (InSb). A significant reduction of electron effective mass from 0.032$m_\mathrm{e}$ to 0.017$m_\mathrm{e}$ is observed in the first 200ps after injecting hot electrons. Measurement of electron effective mass in InSb as a function of photo-injected electron density agrees well with conduction band non-parabolicity predictions from ab initio calculations of the quasiparticle band structure.

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Chelsea Q. Xia, Maurizio Monti, Jessica L. Boland, Laura M. Herz, James Lloyd-Hughes, Marina R. Filip, Michael B. Johnston. 2021-09-11. Hot electron cooling in InSb probed by ultrafast time-resolved terahertz cyclotron resonance. https://doi.org/10.1103/physrevb.103.245205

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