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.
Miniaturization of NIR/SWIR image sensors enabled by thin-film photodiode monolithic integration
In this paper, we present short-wave infrared (SWIR) image sensors with high pixel density. Quantum dot (QD) photodiode stack is monolithically integrated on custom, 130 nm node CMOS readout circuit. State-of-the-art pixel pitch of 1.82 μm is demonstrated in focal plane arrays sensitive at eye-safe region above 1400 nm wavelength. Thin-film photodiode (TFPD) technology will facilitate realization of ultra-compact SWIR sensors for future XR applications, including eye-safe tracking systems and enhanced vision.
Thermal incompatibility analysis of metal-ceramic systems based on flexural displacement data.
The feasibility of simple tests or analytical methods for prediction of residual stress states in metal-ceramic (MC) prostheses has not been demonstrated. Biomaterial metal-ceramic strips have been proposed to provide sensitive measures of transient and residual stress states through the measurement of midpoint deflection after cooling from the ceramic sintering temperature. The objective of this study was to apply the elastic-viscoelastic analogy to calculate transient and residual midpoint deflections in MC biomaterial strips and to compare these values with deflections measured with a beam-bending viscometer (BBV). Calculations and measurements were made for five MC systems that were found from a clinical study to be "thermally compatible" systems. Metal strips, 64 mm in length, 3 mm wide, and either 0.5 mm, 1.0 mm, or 2.0 mm in thickness, were veneered with four 0.25-mm thick layers of opaque porcelain. Midpoint deflection of the MC strips (ceramic oriented in the posterior position) was measured during cooling from an initial temperature of 700 degrees C. In general, the directions of the measured residual deflections did not agree with the "textbook" convention that negative deflections are associated with positive thermal contraction mismatch (alpha(M) - alpha(c) > 0) regardless of metal thickness. For a metal thickness of 0.5 mm, the residual midpoint deflection for all thermal contraction mismatch cases, except one, was positive (upward deflection) whereas the residual midpoint deflections were all negative when the metal thickness was increased to 1 or 2 mm, independent of the thermal contraction mismatch. The best agreement between calculated and measured values of residual midpoint deflection (+16 microns vs. +14 +/- 2.3 microns, respectively was obtained for MC biomaterial strips with a Ni-Cr alloy (0.5 mm thick) while the largest difference (+346 microns vs. +61 +/- 43.8 microns) was obtained for MC bimaterial strips with a Au-Pd allow (0.5 mm thick). In all but one case, changes in deflection direction as a function of metal thickness were correctly predicted by the viscoelastic analysis. The results of this study indicate that a viscoelastic model is useful for estimating thermal compatibility conditions of MC systems.