Light Emission in Metal-Semiconductor Tunnel Junctions: Direct Evidence for Electron Heating by Plasmon Decay.
basic_science · Level V
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- Record sourced from PubMed, PMID 33497237.
- Also identified by DOI 10.1021/acs.nanolett.0c03945 and PMC identifier 7883388.
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Abstract
We study metal-insulator-semiconductor tunnel junctions where the metal electrode is a patterned gold layer, the insulator is a thin layer of Al<sub>2</sub>O<sub>3</sub>, and the semiconductor is p-type silicon. We observe light emission due to plasmon-assisted inelastic tunneling from the metal to the silicon valence band. The emission cutoff shifts to higher energies with increasing voltage, a clear signature of electrically driven plasmons. The cutoff energy exceeds the applied voltage, and a large fraction of the emission is above the threshold, ℏω > <i>eV</i>. We find that the emission spectrum manifests the Fermi-Dirac distribution of the electrons in the gold electrode. This distribution can be used to determine the effective electron temperature, <i>T</i><sub>e</sub>, which is shown to have a linear dependence on the applied voltage. The strong correlation of <i>T</i><sub>e</sub> with the plasmon energy serves as evidence that the mechanism for heating the electrons is plasmon decay at the source metal electrode.