Device design for global shutter operation in a 1.1-μm pixel image sensor and its application to near infrared sensing
Global shutter is a feature of some CMOS image sensors that allows capture of an entire image at a single point in time. We discuss how the device architecture of InVisage’s QuantumFilm enables global shutter operation by controlling the bias on the device stack without an additional transistor, giving high shutter efficiency in a 1.1 μm pixel CMOS image sensor. We use drift-diffusion device simulations to inform our design and reveal device and material properties that are key for carrier selectivity. Based on our device model, we fabricated global-shutter-enabled QuantumFilm devices for near infrared sensing applications and present a characterization of our devices.
Design and characterization of 1.1 micron pixel image sensor with high near infrared quantum efficiency
At the 940 nm wavelength, solar background irradiance is relatively low and device-mounted monochromatic LED emission can be used to illuminate and assess the shape, distance, and optical properties of objects. We report here NIR imaging that outperforms existing CMOS sensors by achieving record 42% quantum efficiency at 940 nm for a 1.1 μm pixel. The rationally engineered material properties of QuantumFilm allow tuning of the spectral response to the desired wavelength to achieve quantum efficiency that exceeds 40%. In addition, the combination of high QE with QuantumFilm’s distinctive film-based electronic global shutter mechanism allows for extremely low illumination power and therefore lowers time-averaged system power when imaging with active illumination.
Optical properties of intrinsic silicon at 300 K
An updated tabulation is presented of the optical properties of intrinsic silicon relevant to solar cell calculations. the absorption coeficient, refractive index and extinction coeficient at 300 K are tabulated over the 0.25-1.45 μm wavelength range at 0.01 μm intervals.