Group IV THz large area emitter based on GeSn alloy.

Area of Science:

• Terahertz (THz) Photonics
• Semiconductor Materials Science
• Integrated Photonics

Background:

• III-V materials excel in THz photoconductive emitters but lack CMOS compatibility.
• CMOS incompatibility and difficult growth conditions hinder large-scale THz emitter production.
• Need for cost-effective, manufacturable THz emitters compatible with standard semiconductor processes.

Purpose of the Study:

• To propose and investigate Germanium-tin (GeSn) alloy as a CMOS-compatible photoconductive material for THz emitters.
• To evaluate the THz radiation performance of GeSn photoconductors fabricated using CMOS-compatible epitaxy.
• To demonstrate the potential of GeSn for mass-producible, cost-effective THz integrated systems.

Main Methods:

• Utilized CMOS-compatible epitaxy to grow GeSn alloy films.
• Characterized the GeSn photoconductor's electrical mobility (518 cm²/V-s) and absorption coefficient (7187 cm⁻¹ at 1560 nm).
• Fabricated and tested a GeSn-based THz emitter.

Main Results:

• Achieved high carrier mobility and absorption in GeSn at telecom wavelengths.
• Demonstrated ultrafast photocurrent generation suitable for THz radiation.
• The GeSn THz emitter exhibited a bandwidth exceeding 2 THz with a 40 dB signal-to-noise ratio.

Conclusions:

• GeSn alloy is a promising candidate for THz photoconductive emitters due to its excellent properties.
• CMOS-compatible fabrication of GeSn enables potential for large-scale, cost-effective THz systems.
• This work highlights the feasibility of integrating advanced THz technology with mainstream CMOS manufacturing.