Dual band sensitivity enhancements of a VO(x) microbolometer array using a patterned gold black absorber

Area of Science:

• Materials Science
• Optoelectronics
• Infrared Technology

Background:

• Vanadium-oxide-based infrared bolometers are crucial for thermal imaging.
• Improving the absorptance of bolometer surfaces is key to enhancing detector performance.
• Existing methods for surface modification can be complex or degrade absorptive properties.

Purpose of the Study:

• To develop and implement a method for selectively patterning infrared-absorbing gold black onto bolometer arrays.
• To evaluate the impact of gold black patterning on the performance of vanadium-oxide infrared bolometers.
• To assess the compatibility of the patterning process with microfabrication techniques.

Main Methods:

• Selective patterning of gold black using metal lift-off techniques.
• Protection of gold black during fabrication using an evaporated oxide layer.
• Integration of patterned gold black with air-bridge bolometer fabrication involving dry-etch removal of polyimide.
• Performance characterization including infrared responsivity and detector noise measurements.

Main Results:

• Gold black patterning successfully preserved high absorptance.
• Infrared responsivity increased by 22% (long-wave IR) and 70% (mid-wave IR).
• Detector noise remained largely unchanged, with a minor ~15% increase in time constant.

Conclusions:

• Selective gold black patterning is an effective method to enhance infrared bolometer performance.
• The fabrication process is compatible with existing microbolometer manufacturing.
• This approach offers a significant improvement in detector sensitivity for infrared applications.