SBIR Phase II: Advancing Beyond the Photodiode - Deep Sub-micron Pixels for Next-generation Image Sensors

This Small Business Innovation Research Phase II project focuses on developing compact camera modules with lower noise and improved contrast using a submicron pixel imaging sensor array. The commercial potential of this project centers on developing compact cameras for endoscopes, navigational and robotic surgical systems and more. Embedding these cameras in endoscope systems, and even the surgical tools themselves, permits new treatments across a broad range of medical specialties that otherwise are not possible. Switching to the minimally invasive forms of some common surgeries could save an estimated $14 billion in healthcare spending. Oncology, urology, gastroenterology, women's health and pediatric medicine are just some of the specialties that will significantly benefit from these ultra-compact cameras. A broader impact will ultimately come from utilizing submicron pixels in unique ways in high density arrays. The sensor?s small size and fast response times offer unique opportunities for spatial and temporal oversampling. The resulting large numbers of pixels can be employed in a compact multi-aperture arrangement to deliver significantly enhanced color mapping over traditional semiconductor imaging arrays, multispectral imaging, 3-dimensional image reconstruction, motion free auto-focusing, or some combination of the above, providing unique applications in medical imaging, defense, robotics, and consumer electronics. The miniaturization of camera systems calls for the continuous shrinking of pixel sizes. At a certain point, however, the maximum photo-electrons a pixel can hold becomes limited, yielding low signal-to-noise ratios and poor dynamic range. This project develops a novel optical sensor that maintains sensitivity down to hundreds of nanometers. As the size of this sensor decreases, the maximum measurable light intensity can remain constant and the signal-to-noise increases, bringing significant improvements to images? dynamic range and color/feature rendition. This result stands in stark contrast to the behavior of conventional pixels where maximum intensity threshold scales down with pixel size and noise increases with decreasing pixel size. Reducing these image sensors to practice requires transitioning from gallium arsenide based devices to silicon. The work focuses on 1) finalizing design parameters, fabrication, and characterization of the electrical properties and optical response of the system and 2) fabrication and characterization of a linear photodetector array for the creation of both linear images and 2-D images assembled from linear images to characterize the noise, contrast and other image quality parameters of the prototype.