Café com Física

Direct-bandgap emission from hexagonal Ge and SiGe alloys

by Dr Silvana Botti (Institut für Festkörpertheorie und -optik, Friedrich-Schiller-University Jena, Germany)

Sala AD1 (Departamento de Física)

Sala AD1

Departamento de Física

Universidade de Coimbra

Silicon crystallized in the usual cubic (diamond) lattice structure has dominated the electronics industry for more than half a century. However, cubic silicon (Si), germanium (Ge) and SiGe alloys are all indirect-bandgap semiconductors that cannot emit light efficiently. The goalof achieving efficient light emission from group-IV materials in silicon technology has been elusive for decades. Here we demonstrate efficient light emission from direct-bandgap hexagonal Ge and SiGe alloys. We measure a sub-nanosecond, temperature-insensitive radiative recombination lifetime and observe an emission yield similar to that of direct-bandgap group-III–V semiconductors. Moreover, we demonstrate that, by controlling the composition of the hexagonal SiGe alloy, the emission wavelength can be continuously tuned over a broad range, while preserving the direct bandgap. Our experimental findings are in excellent quantitative agreement with ab initio theory. Hexagonal SiGe embodies an ideal material system in which to combine electronic and optoelectronic functionalities on a single chip, opening the way towards integrated device concepts and information-processing technologies.

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ID da reunião: 81310717360
Senha: 055056

Organized by

Filipe Veloso e Pedro Costa