Open Access Nano Express

Miniband-related 1.4–1.8 μm luminescence of Ge/Si quantum dot superlattices

VG Talalaev123*, GE Cirlin14, AA Tonkikh14, ND Zakharov1, P Werner1, U Gösele1, JW Tomm2 and T Elsaesser2

Author Affiliations

1 Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle/Saale, Germany

2 Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2A, 12489, Berlin, Germany

3 V.A. Fock Institute of Physics, St. Petersburg State University, Ulyanovskaya 1, 198504 Petrodvorets, St. Petersburg, Russia

4 Ioffe Physico-Technical Institute RAS, 194021, Polytekhnicheskaya 26, St. Petersburg, Russia

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Nanoscale Research Letters 2006, 1:137-153  doi:10.1007/s11671-006-9004-x

Published: 1 August 2006

Abstract

The luminescence properties of highly strained, Sb-doped Ge/Si multi-layer heterostructures with incorporated Ge quantum dots (QDs) are studied. Calculations of the electronic band structure and luminescence measurements prove the existence of an electron miniband within the columns of the QDs. Miniband formation results in a conversion of the indirect to a quasi-direct excitons takes place. The optical transitions between electron states within the miniband and hole states within QDs are responsible for an intense luminescence in the 1.4–1.8 µm range, which is maintained up to room temperature. At 300 K, a light emitting diode based on such Ge/Si QD superlattices demonstrates an external quantum efficiency of 0.04% at a wavelength of 1.55 µm.

Keywords:
73.21.Cd; 73.21.La; 73.40.Gk; 73.63.Kv; 78.67.Hc; 78.67.Pt