Electrically pumped lasing from Ge Fabry-Perot resonators on Si

Area of Science:

• Semiconductor Physics
• Optoelectronics
• Materials Science

Background:

• Germanium (Ge) is a promising material for optoelectronic applications due to its indirect bandgap, which typically hinders light emission.
• Achieving efficient light emission from Ge-based devices is crucial for integrating optical functionalities into silicon photonics.

Purpose of the Study:

• To demonstrate room temperature lasing in electrically pumped n-type doped Ge edge-emitting devices.
• To investigate the optical gain and lasing characteristics of Si-Ge waveguide heterodiodes.
• To explore the influence of device geometry on lasing performance.

Main Methods:

• Fabrication of Si-Ge waveguide heterodiodes using cleaving techniques.
• Characterization of electroluminescence spectra under electrical injection.
• Analysis of optical bleaching and intensity gain.
• Investigation of devices with varying lengths and widths.

Main Results:

• Observation of room temperature lasing in n-type Ge edge emitters.
• Electroluminescence spectra showed optical bleaching and intensity gain between 1660 nm and 1700 nm.
• Lasing threshold was reached with pulsed electrical injection of 500 kA/cm².
• Device geometry was optimized for improved gain-absorption ratios.

Conclusions:

• Electrically pumped n-type Ge edge emitters can achieve room temperature lasing.
• The observed phenomena align with theoretical predictions for n-type Ge.
• Si-Ge waveguide devices offer a viable platform for integrated germanium-based lasers.