Details

Autor(en) / Beteiligte

• Oehme, Michael
• Gollhofer, Martin
• Widmann, Daniel
• Schmid, Marc
• Kaschel, Mathias
• Kasper, Erich
• Schulze, Jörg

Titel

Direct bandgap narrowing in Ge LED's on Si substrates

Ist Teil von

• Optics express, 2013-01, Vol.21 (2), p.2206-2211

Ort / Verlag

United States

Erscheinungsjahr

2013

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• In this paper we investigate the influence of n-type doping in Ge light emitting diodes on Si substrates on the room temperature emission spectrum. The layer structures are grown with a special low temperature molecular beam epitaxy process resulting in a slight tensile strain of 0.13%. The Ge LED's show a dominant direct bandgap emission with shrinking bandgap at the Γ point in dependence of n-type doping level. The emission shift (38 meV at 10²⁰cm⁻³) is mainly assigned to bandgap narrowing at high doping. The electroluminescence intensity increases with doping concentrations up to 3x10¹⁹cm⁻³ and decreases sharply at higher doping levels. The integrated direct gap emission intensity increases superlinear with electrical current density. Power exponents vary from about 2 at low doping densities up to 3.6 at 10²⁰cm⁻³ doping density.