Open-access IEEE Journal of the Electron Devices Society publishes an early-access paper "A Pump-gate Jot Device with High Conversion Gain for a Quanta Image Sensor" by Jiaju Ma and Eric Fossum. The new jot sensor uses BSI pixel with charge stored under TG:
A special precaution has been made to reduce the FD capacitance by spacing it away from TG and making RST gate of trapezoidal shape:
The simulated CG of the jot is 380uV/e for a 1.4um pixel in 65nm process (FD capacitance of 0.4fF). The work was sponsored by Rambus.