Sensing Infrared Photons at Room Temperature: From Bulk Materials to Atomic Layers

Abstract

Room-temperature operating means a profound reduction of volume, power consumption, and cost for infrared (IR) photodetectors, which promise a wide range of applications in both military and civilian areas, including individual soldier equipment, automatic driving, etc. Inspired by this fact, since the beginning of 1990s, great efforts have been made in the development of uncooled thermal detectors. During the last two decades, similar efforts have been devoted using IR photon detectors, especially based on photovoltaic effects. Herein, the proven technologies, which have been commercialized with a large format, like InGaAs/InP pin diodes, InAsSb barrier detectors, and high-operating-temperature HgCdTe devices, are reviewed. The newly developed technology is emphasized, which has shown unique superiority in detecting mid-wavelength and long-wavelength IR signals, such as quantum cascade photodetectors. Finally, brand-new concept devices based on 2D materials are introduced, which are demonstrated to provide additional degrees of freedom in designing and fabricating room-temperature IR devices, for example, the construction of multi-heterojunctions without introducing lattice strain, the convenient integration of optical waveguides and electronic gratings. All information provided here aims to supply a full view of the progress and challenges of room-temperature IR detectors.has its own IR radiation characteristic which contains a wealth of information. For thousands of years, people have studied the visible light as the sensory spectrum of the human eye is only 380-740 nm. But for the invisible IR, people did not know it until the British astronomer Herschel discovered it with a blackened mercury thermometer over 200 years ago, since then the IR technology had developed slowly because people were not aware of the importance of IR in the next 100 years. [1,2] During World War II, PbS IR detectors for the first time were applied on battleships as a "top-secret" instrument, thus people began to focus research on IR technology. In comparison with visible, IR technology has unique characteristics:better environmental adaptability, stronger anti-interference ability, and higher resolution capability. With advantages of working at night or in harsh weather, transmitting information securely, and identifying the camouflaged target accurately, the IR detectors have been researched and widely applied in military, national defense, bioscience, and other momentous fields. [3][4][5] In the historical development of IR photo detectors, the response spectral is being extended to longer wavelengths; the pixels of imaging have been expanded from single element to tens of millions; the operating temperatures of cooled IR detectors are being increased to be closer to room temperature. [6][7][8] Nowadays, the remote IR imaging becomes clearer; the noise-equivalent temperature difference (NETD) of IR detection systems can reach 10 mK [9] or even lower; and IR detection systems become more and more integrated. [10] However, most high-...

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