Microstructuring to Improve the Thermal Stability of GeSn Layers.

Area of Science:

• Materials Science
• Semiconductor Physics
• Nanotechnology

Background:

• Tin segregation in Germanium-Tin (GeSn) alloys is a critical challenge limiting device applications.
• High Sn concentrations are desirable for advanced optoelectronic properties but exacerbate segregation issues.

Purpose of the Study:

• To investigate the effect of microstructuring on tin segregation in GeSn alloys during thermal annealing.
• To explore the potential of microstructuring for stabilizing high Sn concentration GeSn layers.

Main Methods:

• Fabrication of GeSn microdisks with up to 16.9% Sn concentration.
• Annealing experiments at 400 °C for 20 min, comparing microdisks with blanket layers.
• Analysis of elemental composition and photoluminescence properties post-annealing.

Main Results:

• GeSn microdisks showed no tin segregation after annealing, unlike blanket layers.
• Elemental composition remained unchanged, and photoluminescence was enhanced without energy shifts.
• Microstructuring effectively stabilized high Sn concentration GeSn layers at elevated temperatures.

Conclusions:

• Microstructuring provides a novel strategy to prevent Sn segregation in GeSn alloys.
• This approach allows for thermal annealing to improve GeSn properties for optoelectronics.
• The strategy is applicable to other metastable alloys requiring high-temperature processing.