Startup starts sampling ‘large-wafer’ photodetectors

Technology News | March 28, 2023

By Peter Clarke

Optoelectronic sensor startup Aeluma Inc. (Golera, Calif.) has started sampling photodetectors to a “tier-1” automotive supplier.

Founded in 2019, Aeluma has developed technology that combines compound semiconductor optoelectronics with what it calls “large-diameter” silicon wafer manufacturing. The company has not explicitly said whether it is supporting 200mm or 300mm wafers.

However, Aeluma states the technology can be used for lidar sensors communication, mobile, AR/VR, quantum computing, and AI. Manufacturing photodetectors on wafers larger than competitors would provide a cost advantage.

Aeluma claims its latest photodetector experiments demonstrate the potential for high quantum efficiency and low dark current at temperatures up to 105 degrees C, necessary for automotive specifications. These sensors achieve low dark current of less than 100 picoamperes (pA) and quantum efficiency greater than 90 percent.

Best of both worlds

Lidar applications typically use either silicon SPADs (single-photon avalanche diode) and InGaAs (indium gallium arsenide) photodiodes. While SPADs are produced on large wafers in high volumes they typically have lower efficiency than InGasAs photodiodes. Also they operate in the 905nm to 940nm wavelength region which requires low laser power for eye safety. This in turn limits lidar range. Increasing the photodetector efficiency in this band would improve lidar performance.

The alternative InGaAs can operate across the range from 900nm to 1700nm including the 1550nm region used for long-range lidar. Eye safety can be maintained at significantly higher laser power at 1550nm, therefore enabling better resolution at longer distances.

Thus, Aeluma’s technology spans the 900nm to 1700nm range and can improve the cost efficiency at 1550nm and improve the performance at 905nm to 940nm.

The company has its own 9,000 square foot manufacturing cleanroom at its headquarters in Goleta, California.

In December 2022 Aeluma raised $1.551 million from the initial closing of a private placement of the company’s common stock at a purchase price of $3.00 per share.