PhD Thesis Defense: Jiaju Ma

Monday, June 19, 2017, 10:00am

Jackson Conference Room, Cummings Hall

“Photon-Counting Jot Devices for Quanta Image Sensor”


The quanta image sensor (QIS) is a third-generation solid-state digital imaging technology. The photoelements, called “jots,” are specially engineered to do photon-counting at room temperature without using electron avalanche gain. A QIS may contain billions of jots operating at 1000fps or higher. By counting every single photon at a high speed, numerous exciting features are enabled. This novel technology can naturally fit the needs of high-speed and high-resolution accurate photon-counting imaging for scientific imaging, space imaging, security, low-light imaging and other applications.

The proof of concept for the jot device was successfully developed in 2015 and 2017. With the innovative jot devices, sub-0.2e- r.m.s. read noise was demonstrated with manifestly improved conversion gain at room temperature. For the first time, accurate photon counting was realized with photodetectors fabricated in a CMOS process without the use of amplification from electron multiplication.

This thesis concludes the development of the photon-counting jot devices for the QIS. The design of the jot was one of the most difficult challenges in the implementation of the QIS. These difficulties included the reduction of read noise to enable photon-counting while shrinking the size of the jots and optimizing other figures of merit that affect the accuracy of photon-counting (dark current, quantum efficiency, etc.). The work presented in this thesis covers all of these topics, while the emphasis is placed on the most challenging hurdle: the reduction of read noise towards the deep sub-electron read noise region to enable photon-counting.

Thesis Committee

For more information, contact Daryl Laware at