Quantum-confined Stark effect measurements in Ge/SiGe quantum-well structures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Optoelectronics

Background:

• Quantum-confined Stark effect (QCSE) is crucial for optoelectronic devices.
• Germanium/Silicon-Germanium (Ge/SiGe) multiple quantum wells (MQWs) offer potential for novel photonic applications.
• Understanding QCSE in Ge/SiGe MQWs is key for device optimization.

Purpose of the Study:

• To investigate the room-temperature quantum-confined Stark effect in Ge/SiGe MQWs.
• To accurately determine the light absorption characteristics of the MQWs.
• To analyze the influence of electric fields on exciton absorption peaks.

Main Methods:

• Growth of Ge/SiGe MQWs using low-energy plasma-enhanced chemical vapor deposition.
• Fabrication of the active region within a p-i-n diode structure.
• Optical transmission, photocurrent, and differential transmission spectroscopy under varying reverse bias voltages.

Main Results:

• Accurate measurement of the fraction of light absorbed per well in Ge/SiGe MQWs.
• Observation of both Stark shift and reduction in exciton absorption peak intensity.
• Differential transmission measurements confirmed no thermal contribution to the observed effects.

Conclusions:

• The study provides a comprehensive analysis of the room-temperature QCSE in Ge/SiGe MQWs.
• The results offer valuable insights for designing and improving Ge/SiGe-based optoelectronic devices.
• The findings highlight the potential of these MQWs for tunable optical applications.