Extended Defect Propagation in Highly Tensile-Strained Ge Waveguides



Tensile-strained Ge is a possible laser material for Si integrated circuits, but reports of lasers using tensile Ge show high threshold current densities and short lifetimes. To study the origins of these shortcomings, Ge ridge waveguides with tensile strain in three dimensions were fabricated using compressive silicon nitride (SiNx) films with up to 2 GPa stress as stress liners. A Raman peak shift of up to 11 cm(-1) was observed, corresponding to 3.6% hydrostatic tensile strain for waveguides with a triangular cross-section. Real time degradation in tensile-strained Ge was observed and studied under transmission electron microscopy (TEM). A network of defects, resembling dark line defects, was observed to form and propagate with a speed and density strongly correlated with the local strain extracted from both modeled and measured strain profiles. This degradation suggests highly tensile-strained Ge lasers are likely to have significantly shorter lifetime than similar GaAs or InGaAs quantum well lasers.


Attribute NameValues
  • Meng Qi

  • William O'Brien

  • Chad Stephenson

  • Victor Patel

  • Ning Cao

  • Brian Thibeault

  • Marco Schowalter

  • Andreas Rosenauer

  • Vladimir Protasenko

  • Huili Xing

  • Mark Wistey

Journal or Work Title
  • Crystals

  • 7

  • 6

First Page
  • 157

  • 20731-4352

Publication Date
  • 2017-05

  • MDPI

Date Created
  • 2018-12-07

  • English

Departments and Units
Record Visibility Public
Content License
  • All rights reserved

Digital Object Identifier


This DOI is the best way to cite this article.