Jiaju Ma

Quanta Image Sensor Jot With Sub 0.3e- r.m.s. Read Noise and Photon Counting Capability

The first quanta image sensor jot with photon counting capability is demonstrated. The low-voltage device demonstrates less than 0.3e- r.m.s. read noise on a single read out without the use of avalanche gain and single-electron signal quantization is observed. A new method for determining read noise and conversion gain is also introduced.

Characterization of Quanta Image Sensor Pump-Gate Jots With Deep Sub-Electron Read Noise

Characterization of quanta image sensor pixels with deep sub-electron read noise is reported. Pixels with conversion gain of

A Pump-Gate Jot Device With High Conversion Gain for a Quanta Image Sensor

423\mu \text{V}

A 2.5 pJ/b Binary Image Sensor as a Pathfinder for Quanta Image Sensors

/e- and read noise as low as 0.22e- r.m.s. were measured. Dark current is 0.1e-/s at room temperature, and lag less than 0.1e-. This is one of the first works reporting detailed characterization of image sensor pixels with mean signals from sub-electron (0.25e-) to a few electrons level. Such pixels in a nearly-conventional CMOS image sensor process will allow realization of photon-counting image sensors for a variety of applications.

Jot devices and the Quanta Image Sensor

A new photodetector designed for Quanta image sensor application is proposed. The photodetector is a backside-illuminated, buried photodiode with a vertically integrated pump and transfer gate and a distal floating diffusion to reduce parasitic capacitance. The structure features compact layout and high conversion gain. The proposed device is modeled and simulated, and its performance characteristics estimated.

The Quanta Image Sensor: Every Photon Counts.

This paper presents a pathfinder binary image sensor for exploring low-power dissipation needed for future implementation of gigajot single-bit quanta image sensor (QIS) devices. Using a charge-transfer amplifier design in the readout signal chain and pseudostatic clock gating units for row and column addressing, the 1-Mpixel binary image sensor operating at 1000 frames/s dissipates only 20-mW total power consumption, including I/O pads. The gain and analog-to-digital converter stages together dissipate 2.5 pJ/b, successfully paving the way for future gigajot QIS sensor designs.

Quanta Image Sensor (QIS): Early Research Progress

The Quanta Image Sensor (QIS) concept and recent work on its associated jot device are discussed. A bipolar jot and a pump-gate jot are described. Both have been modelled in TCAD. As simulated, the pump-gate jot has a full well of 200e- and conversion gain of 480uV/e-.

A 1 μm-Pitch Quanta Image Sensor Jot Device With Shared Readout

The Quanta Image Sensor (QIS) was conceived when contemplating shrinking pixel sizes and storage capacities, and the steady increase in digital processing power. In the single-bit QIS, the output of each field is a binary bit plane, where each bit represents the presence or absence of at least one photoelectron in a photodetector. A series of bit planes is generated through high-speed readout, and a kernel or “cubicle” of bits (x, y, t) is used to create a single output image pixel. The size of the cubicle can be adjusted post-acquisition to optimize image quality. The specialized sub-diffraction-limit photodetectors in the QIS are referred to as “jots” and a QIS may have a gigajot or more, read out at 1000 fps, for a data rate exceeding 1 Tb/s. Basically, we are trying to count photons as they arrive at the sensor. This paper reviews the QIS concept and its imaging characteristics. Recent progress towards realizing the QIS for commercial and scientific purposes is discussed. This includes implementation of a pump-gate jot device in a 65 nm CIS BSI process yielding read noise as low as 0.22 e− r.m.s. and conversion gain as high as 420 µV/e−, power efficient readout electronics, currently as low as 0.4 pJ/b in the same process, creating high dynamic range images from jot data, and understanding the imaging characteristics of single-bit and multi-bit QIS devices. The QIS represents a possible major paradigm shift in image capture.

Room temperature 1040fps, 1 megapixel photon-counting image sensor with 1.1um pixel pitch

Early research progress in the realization of the Quanta Image Sensor is reported. Simulation of binary data acquisition and image formation was performed. Initial analysis and simulation of a readout signal chain has been performed and bounds on power dissipation established. Photodetector device concepts have been explored using TCAD.

Analytical Modeling and TCAD Simulation of a Quanta Image Sensor Jot Device With a JFET Source-Follower for Deep Sub-Electron Read Noise

Characterization of a 1 μm-pitch, four-way shared readout quanta image sensor jot device is reported. The jot device achieved 0.48e- r.m.s. read noise with 230 μV/econversion gain. Quantum efficiency, dark current, and lag results are discussed. Cross-talk was investigated using TCAD simulation and the results are analyzed.