Infrared Photodetectors

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Abstract  This technology uses a novel approach that allows the IR light to be strongly absorbed by the metal structures, rather than the low band gap materials. This invention makes use of metal metasurfaces that can be fabricated by scalable, inexpensive techniques and achieve a broad-band IR absorption of over 95% in 15-nm-thick metal films.     Background Infrared (IR) photodetectors have a wide range of uses in areas such as communications and remote sensing. They can range from simple devices from being embedded into automatic doors, to remote controls, to even more complex applications such as arrays to help astronomers detect radiation within the universe, as well as fiber optic communications. Conventionally, photonic IR detectors employ low band gap materials such as InGaAs, InSb, or HgCdTe; however, these materials include elements that are rare, expensive, or toxic.  Past research indicates that silicon, which is a much cheaper and more abundant element, could be used for IR detection when metal electrodes are cleverly nanostructured.  However, in this case, expensive techniques such as electron beam lithography have been used to fabricate the structures.  Though, for mass production, it is important to obtain metallic structures that do not require expensive techniques and tolerate practical fabrication errors. A current market need exists for advanced photodetectors that are inexpensive, non-toxic, and can achieve large absorption volume.    Description Researchers at the University of New Mexico have developed a new method of trapping light within hot electron based silicon infrared photodetectors. This technology uses a novel approach that allows the IR light to be strongly absorbed by the metal structures, rather than the low band gap materials. This invention makes use of metal metasurfaces that can be fabricated by scalable, inexpensive techniques and achieve a broad-band IR absorption of over 95% in 15-nm-thick metal films.     Advantages Novel, efficient photonic infrared detector Unprecedented strong absorption, in terms of both the absorptance magnitude and the band width Because light is absorbed during multiple passes in this new scheme, the metal structures do not have to be fabricated with very high precision  With the dielectric layer, various metals, such as aluminum, gold, and silver, can be used for the back reflector without a significant difference in absorption in the metal Provides scalable inexpensive techniques that can achieve a broad band IR absorption of over 95% in 15-nm-thick metal films