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Multiband Charge-Coupled Device

Abstract: Optical astronomical observation is one of our primary tools for answering fundamental physical questions, such as the Universe's formation, evolution and fate. While existing theories have proved insufficient, large-scale data from deep, optical, multi-color surveys are required to distinguish emerging, competing theories. However, today's color imaging methods require the use of band-pass filters or other wavelength selecting optics, because common image sensors are monochromatic. This paradigm is fundamentally inefficient, because astronomical sources are typically broadband and most photons are wasted during wavelength selection. The multiband charge-coupled device (CCD) is introduced to circumvent the aforementioned limitation. It is a polychromatic image sensor fabricated on semiconductor-on-insulator (SOI) substrates with multiple device layers. It can be multifold more sensitive than a conventional CCD, because photons are collected and spectrally resolved in the substrate without external optics. The improved sensitivity can benefit all filter-based color imaging systems, especially those that are limited by low-light imaging efficiency, such as optical astronomical telescopes. I will present the first experimental demonstration of multiband light absorption and charge extraction for a three-layer, front-illuminated, single-pixel device. Its design, simulation, fabrication and testing will be described. The ratio of the active layers' measured responsivities changes with wavelength, indicating that incident color information is captured in the multilayer SOI substrate. This result is an important step toward the realization of a full-scale multiband CCD.
Speaker: Chu-En Chang - Stanford University School of Medicine, Neurobiology
Speaker Bio:
Poster Link: Poster