Engineering Slow-Carrier Interfacial Recombination Enables Tailored Spectral Response

Area of Science:

• Optoelectronics
• Semiconductor physics
• Materials science

Background:

• Photocarrier surface recombination is a key factor in optoelectronic device performance.
• Understanding carrier dynamics at semiconductor interfaces is crucial for device optimization.

Purpose of the Study:

• To investigate the preferential recombination of slower photocarriers at semiconductor surfaces.
• To demonstrate the engineering of photocarrier recombination for novel optoelectronic functionalities.

Main Methods:

• Generating photocarriers in semiconductors with wide space-charge regions and varying electric potentials.
• Analyzing carrier collection rates and dynamics at different interfaces (direct contacts, defect-engineered surfaces, organic contacts).
• Intentionally impeding photocarrier transport to study recombination selectivity.

Main Results:

• Slower photocarriers, arising from weaker electric fields, exhibit higher probabilities of being trapped by defect states and recombining.
• Carriers generated in low electric potential regions show preferential recombination.
• Demonstrated a silicon narrowband photodetector with approximately 100 nm FWHM by manipulating slow-carrier recombination.

Conclusions:

• Semiconductor surfaces and interfaces act as natural filters, capturing slow carriers with weak drift.
• Engineering slow-carrier recombination offers a pathway to tailor spectral responses in semiconductor heterointerfaces.
• This work unlocks emergent optoelectronic functionalities by controlling photocarrier surface recombination.