29 GHz single-mode vertical-cavity surface-emitting lasers passivated by atomic layer deposition

Area of Science:

• Optoelectronics
• Materials Science
• Semiconductor Devices

Background:

• Fabrication of high-speed single-mode (SM)-vertical-cavity surface-emitting lasers (VCSELs) faces challenges in complexity, cost, reliability, and yield.
• These issues hinder the high-volume processing and mass commercialization of SM-VCSELs for datacom and other applications.

Purpose of the Study:

• To investigate the effects of Al2O3 passivation films deposited by atomic layer deposition (ALD) on the mesa sidewalls of high-speed 850-nm SM-VCSELs.
• To demonstrate ALD passivation as a method to improve SM-VCSEL performance and enable mass production.

Main Methods:

• Deposition of Al2O3 passivation films using atomic layer deposition (ALD) on the mesa sidewalls of high-speed 850-nm SM-VCSELs.
• Characterization of static performance improvements and modulation bandwidth.
• Development of an improved microwave small-signal equivalent circuit model for SM-VCSELs.

Main Results:

• ALD-deposited Al2O3 films alleviate carrier trapping by sidewall defects.
• ALD-passivated SM-VCSELs exhibit statistically significant static performance improvements.
• A record-breaking SM-modulation bandwidth of 29.1 GHz was achieved.

Conclusions:

• ALD passivation effectively mitigates processing-induced surface damage in SM-VCSELs.
• This technique enhances SM-VCSEL performance, including modulation bandwidth.
• ALD passivation is a viable strategy for mass production of high-quality SM-VCSELs for optical interconnects.