J 2021

Light emission from direct band gap germanium containing split-interstitial defects

MURPHY-ARMANDO, Felipe, Moritz BREHM, Petr STEINDL, Mark LUSK, T. FROMHERZ et. al.

Basic information

Original name

Light emission from direct band gap germanium containing split-interstitial defects

Authors

MURPHY-ARMANDO, Felipe, Moritz BREHM, Petr STEINDL (203 Czech Republic, belonging to the institution), Mark LUSK, T. FROMHERZ, Karlheinz SCHWARZ and Peter BLAHA

Edition

Physical Review B, The American Physical Society, 2021, 2469-9950

Other information

Language

English

Type of outcome

Article in a journal

Field of Study

10302 Condensed matter physics

Country of publisher

United States of America

Confidentiality degree

is not subject to a state or trade secret

References:

Impact factor

Impact factor: 3.908

RIV identification code

RIV/00216224:14310/21:00121241

Organization unit

Faculty of Science

DOI

UT WoS

000621592900005

Keywords in English

Spontaneous emission; k dot p method; Electronic structure; first-principles calculations; interstitials

Tags

Tags

International impact, Reviewed
Changed: 22/3/2021 16:36, Mgr. Marie Novosadová Šípková, DiS.

Abstract

V originále

The lack of useful and cost-efficient group-IV direct band gap light emitters still presents the main bottle-neck for complementary metal-oxide semiconductor-compatible short-distance data transmission, single-photon emission, and sensing based on silicon photonics. Germanium, a group-IV element like Si, is already widely used in silicon fabs. While the energy band gap of Ge is intrinsically indirect, we predict that the insertion of Ge-Ge split-[110] interstitials into crystalline Ge can open up a direct band gap transmission path. Here, we calculate from first principles the band structure and optical emission properties of Ge, Sb, and Sn split-[110] interstitials in bulk and low-dimensional Ge at different doping concentrations. Two types of electronic states provide the light-emission enhancement below the direct band gap of Ge: a hybridized L-Gamma state at the Brillouin zone center and a conduction band of Delta band character that couples to a raised valence band along the Gamma-X direction. Majority carrier introduced to the system through doping can enhance light emission by saturation of nonradiative paths. Ge-Sn split interstitials in Ge shift the top of the valence band towards the Gamma-X direction and increase the Gamma character of the L-Gamma state, which results in a shift to longer emission wavelengths. Key spectral regions for datacom and sensing applications can be covered by applying quantum confinement in defect-enhanced Ge quantum dots for an emission wavelength shift from the midinfrared to the telecom regime.