Control of Spectral Photosensitivity in Stacked Color Sensors: Proposal and Theoretical Analysis

Abstract

To capture a realistic and pleasing full-color two-dimensional representation of a scene, we propose and analyze stacked color sensors that incorporate a distributed Bragg reflector (DBR) with a phase-compensation layer between a blue absorption layer and a green absorption layer. Because incident light on color sensors is not coherent, photosensitivity is calculated for partially coherent light. In the blue absorption region, it is found that the peak wavelength mainly depends on the thickness of the blue absorption layer, and the spectral width is dominantly controlled by the Bragg wavelength λB of the DBR when λB > 0.4 µm. It is also revealed that the phase-compensation layer plays an important role in controlling the spectral shape of the photosensitivity. From the viewpoint of a measure of the goodness, the Bragg wavelength λB and the thickness of each absorption layer are optimized for bare color sensors and color sensors capped with an IR cutoff filter.