Pseudomorphic GeSiSn, SiSn and Ge layers in strained heterostructures

Area of Science:

• Materials Science
• Semiconductor Physics
• Surface Science

Background:

• Germanium-Silicon-Tin (GeSiSn) and Silicon-Tin (SiSn) alloys are promising for advanced electronic and optoelectronic devices.
• Understanding their growth mechanisms on Silicon (Si) substrates is crucial for controlling film properties.

Purpose of the Study:

• To investigate the growth mechanisms of GeSiSn and SiSn layers on Si(100).
• To establish kinetic and phase diagrams for these materials.
• To explore their potential for direct bandgap applications.

Main Methods:

• Kinetic and phase diagram construction.
• Specular beam oscillation monitoring during film growth.
• Transmission Electron Microscopy (TEM) and X-ray Diffractometry (XRD).
• Photoluminescence (PL) spectroscopy.
• Reciprocal space mapping (RSM).
• Band structure calculations.

Main Results:

• Kinetic diagrams for GeSiSn/SiSn film states and a phase diagram for Sn/Si(100) were established.
• Specular beam oscillations observed for SiSn films (150-300 °C, up to 35% Sn), indicating crystal perfection.
• Pseudomorphic GeSiSn/SiSn films with smooth heterointerfaces confirmed by TEM and XRD.
• Photoluminescence detected (0.6-0.8 eV) in GeSiSn/Si heterostructures, suggesting type II band alignment.
• Tensile strained Ge films (0.86%-1.5% strain) created on GeSn layers.
• Calculations identified Sn content ranges for direct bandgap GeSiSn, SiSn, and GeSn materials.

Conclusions:

• Precise control over GeSiSn and SiSn growth on Si(100) is achievable.
• These materials exhibit excellent crystalline quality and interface properties.
• The findings support the development of direct bandgap germanium alloys for optoelectronic applications.