Investigation of germanium quantum-well light sources

Area of Science:

• Optoelectronics
• Materials Science
• Quantum Engineering

Background:

• Germanium (Ge) quantum wells are crucial for optoelectronic devices.
• Understanding their optical properties is key to improving device performance.
• Previous studies have explored Ge quantum wells, but a comprehensive optical analysis is needed.

Purpose of the Study:

• To investigate the optical properties of germanium (Ge) quantum-well devices.
• To analyze the impact of increased carrier density on recombination rates.
• To quantify optical loss in Ge quantum-well structures.

Main Methods:

• Device simulations to predict carrier density.
• Photoluminescence (PL) measurements to assess radiative recombination.
• Electroluminescence (EL) measurements to determine temperature-dependent properties.
• Tapered-fiber collection method for PL measurements of microdisks.

Main Results:

• Simulations confirmed a significant increase in carrier density within Ge quantum wells.
• PL measurements revealed enhanced direct-bandgap radiative recombination rates.
• EL measurements showed temperature-dependent properties consistent with theoretical models.
• Optical loss in the Ge quantum-well structure was quantified using PL spectra for the first time.

Conclusions:

• Increased carrier density in Ge quantum wells enhances radiative recombination.
• The developed theoretical models accurately predict device behavior.
• Quantifying optical loss provides critical data for future device optimization.