Unraveling electronic band structure of narrow-bandgap p-n nanojunctions in heterostructured nanowires
Journal article, 2021

The electronic band structure of complex nanostructured semiconductors has a considerable effect on the final electronic and optical properties of the material and, ultimately, on the functionality of the devices incorporating them. Valence electron energy-loss spectroscopy (VEELS) in the transmission electron microscope (TEM) provides the possibility of measuring this property of semiconductors with high spatial resolution. However, it still represents a challenge for narrow-bandgap semiconductors, since an electron beam with low energy spread is required. Here we demonstrate that by means of monochromated VEELS we can study the electronic band structure of narrow-gap materials GaSb and InAs in the form of heterostructured nanowires, with bandgap values down to 0.5 eV, especially important for newly developed structures with unknown bandgaps. Using complex heterostructured InAs-GaSb nanowires, we determine a bandgap value of 0.54 eV for wurtzite InAs. Moreover, we directly compare the bandgaps of wurtzite and zinc blende polytypes of GaSb in a single nanostructure, measured here as 0.84 and 0.75 eV, respectively. This allows us to solve an existing controversy in the band alignment between these structures arising from theoretical predictions. The findings demonstrate the potential of monochromated VEELS to provide a better understanding of the band alignment at the heterointerfaces of narrow-bandgap complex nanostructured materials with high spatial resolution. This is especially important for semiconductor device applications where even the slightest variations of the electronic band structure at the nanoscale can play a crucial role in their functionality.


Reza Zamani

Chalmers, Physics, Microstructure Physics

Lund University

Fredrik S. Hage

University of Oxford

Daresbury Laboratory

University of Oslo

Alberto Eljarrat

Humboldt University of Berlin

Luna Namazi

Lund University

Quentin M. Ramasse

Daresbury Laboratory

University of Leeds

Kimberly A. Dick

Lund University

Physical Chemistry Chemical Physics

1463-9076 (ISSN) 1463-9084 (eISSN)

Vol. 23 44 25019-25023

Subject Categories

Atom and Molecular Physics and Optics

Other Physics Topics

Condensed Matter Physics





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