Canon on Large Pixel Design Challenges

Canon whitepaper "Advances in CMOS Image Sensors and Associated Processing" by Shin Kikuchi, Daisuke Kobayashi, Hitoshi Yasuda, Hajime Ueno, and Laurence Thorpe, first presented at the Hollywood Professional Alliance (HPA) Tech Retreat in Palm Springs on February 19, 2016 talks about challenges in 19um large pixel design (note a strange definition of conversion gain, probably meant to be image lag):

The image sensor design sought optimization of three key attributes of the photosite:
1. Sensitivity – determined by the quantum efficiency of the photosite
2. Saturated charge quantity (sometimes termed full well capacity) – that determines dynamic range
3. Efficiency of the charge transfer (sometimes termed conversion gain) – the goal being to transfer all electrons during each reset period to ensure full sensitivity

Canon says it was able to achieve 70% QE at 500nm in monochrome sensor.

The continuation of the whitepaper, mostly about extended DR and dual pixel is available here.