Experimental determination of the bare energy gap of GaAs without the zero-point renormalization

Abstract

The energy gap of simple band insulators like GaAs is a strong function of temperature due to the electron-phonon interactions. Interestingly, the perturbation from zero-point phonons is also predicted to cause significant (a few percent) renormalization of the energy gap at absolute zero temperature but its value has been difficult to estimate both theoretically and, of course, experimentally. Given the experimental evidence [Bhattacharya, et al., Phys. Rev. Lett. 114, 047402 (2015)] that strongly supports that the exponential broadening (Urbach tail) of the excitonic absorption edge at low temperatures is the manifestation of this zero temperature electron-phonon scattering, we argue that the location of the Urbach focus is the zero temperature unrenormalized gap. Experiments on GaAs yield the zero temperature bare energy gap to be 1.581 eV and thus the renormalization is estimated to be 66 meV.

arXiv commentIncludes Supplementary Data. To appear in Journal of Physics: Condensed Matter as a Letter

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Cited by in corpus (2)

• Carrier thermalization and zero-point bandgap renormalization in halide perovskites from the Urbach tails of the emission spectrum
• Renormalization of the optical band gap through an effective Thirring interaction for massive Dirac-like electrons