Electroluminescence from Strained Ge membranes and Implications for an Efficient Si-Compatible Laser

TL;DR

This paper demonstrates room-temperature electroluminescence from highly strained germanium membranes, showing improved electrical performance and spectral shifts, with implications for developing efficient silicon-compatible lasers.

Contribution

It introduces a novel strain application technique to Ge membranes, enhancing electroluminescence and providing insights into Ge laser development.

Findings

Increased on-off ratio by an order of magnitude in strained Ge LEDs

Redshift of 100nm in EL spectrum due to strain

Simulation insights into Ge laser efficiency

Abstract

We demonstrate room-temperature electroluminescence (EL) from light-emitting diodes (LED) on highly strained germanium (Ge) membranes. An external stressor technique was employed to introduce a 0.76% bi-axial tensile strain in the active region of a vertical PN junction. Electrical measurements show an on-off ratio increase of one order of magnitude in membrane LEDs compared to bulk. The EL spectrum from the 0.76% strained Ge LED shows a 100nm redshift of the center wavelength because of the strain-induced direct band gap reduction. Finally, using tight-binding and FDTD simulations, we discuss the implications for highly efficient Ge lasers.