Gamma bandgap determination in pseudomorphic GeSn layers grown on Ge with up to 15% Sn content

Alban Gassenq (1) , L. Milord (2) , J. Aubin (2) , Kevin Guilloy (1) , Samuel Tardif (3) , Nicolas Pauc (1) , Johan Rothman (2) , Alexei Chelnokov (2) , Jean-Michel Hartmann (4) , Vincent Reboud (4) , Vincent Calvo (1)

1 SiNaps - Silicon Nanoelectronics Photonics and Structures
2 DOPT - Département d'Optronique
3 NRS - Nanostructures et Rayonnement Synchrotron
4 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information

Adding Tin (Sn) to Germanium (Ge) can turn it into a direct bandgap group IV semiconductor emitting in the mid-infrared wavelength range. Several approaches are currently being investigated to improve the GeSn devices. It has been theoretically predicted that the strain can improve their optical properties. However, the impact of strain on band parameters has not yet been measured for really high Sn contents (i.e., above 11%). In this work, we have used the photocurrent and photoluminescence spectroscopy to measure the gamma bandgap in compressively strained GeSn layers grown on Ge buffers. A good agreement is found with the modeling and the literature. We show here that the conventional GeSn deformation potentials used in the literature for smaller Sn contents can be applied up to 15% Sn. This gives a better understanding of strained-GeSn for future laser designs. Published by AIP Publishing.

Keywords: Misfit Dislocations; Silicon Photonics; Light-Emission; Germanium

Domains: Physics [physics]

Alban Gassenq, L. Milord, J. Aubin, Kevin Guilloy, Samuel Tardif, et al.. Gamma bandgap determination in pseudomorphic GeSn layers grown on Ge with up to 15% Sn content. Applied Physics Letters, 2016, 109 (24), pp.242107. ⟨10.1063/1.4971397⟩. ⟨cea-01849849⟩