Stability of Tensile-Strained Ge Studied by Transmission Electron Microscopy

Qi, Ming; O'Brien, William A.; Stephenson, Chad A.; Cao, Ning; Thibeault, B.J.; Wistey, Mark A.

doi:10.1109/istdm.2012.6222505

Cited by 2 publications

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“…Little wavelength shift was observed for weakly strained waveguides, while highly strained waveguides had weak PL intensity. 300 K data is © 2012 IEEE and reprinted, with permission, from IEEE Proceedings [1].…”

Section: Figurementioning

confidence: 99%

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Extended Defect Propagation in Highly Tensile-Strained Ge Waveguides

O'Brien

Stephenson

et al. 2017

Crystals

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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 (SiN x ) 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.

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Section: Figurementioning

confidence: 99%

“…Tensile-strained germanium has been studied as a possible laser material due to its nearly-direct bandgap [1,2] and its compatibility with conventional silicon integrated circuit fabrication [3][4][5][6]. Theoretically, a tensile strain of 0.7% (hydrostatic) or 1.4% (biaxial) could produce a direct bandgap in Ge [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%