The detection of photons underpins imaging, spectroscopy, fibre-optic communications and time-gated distance measurements. Nanostructured materials are attractive for detection applications because they can be integrated with conventional silicon electronics and flexible, large-area substrates, and can be processed from the solution phase using established techniques such as spin casting, spray coating and layer-by-layer deposition. In addition, their performance has improved rapidly in recent years. Here we review progress in light sensing using nanostructured materials, focusing on solution-processed materials such as colloidal quantum dots and metal nanoparticles. These devices exhibit phenomena such as absorption of ultraviolet light, plasmonic enhancement of absorption, size-based spectral tuning, multiexciton generation, and charge carrier storage in surface and interface traps.

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Nanostructured materials for photon detection

http://antonirogalski.com/wp-content/uploads/2011/12/Infrared-detectors-Status-and-trends.pdf

Infrared detectors: status and trends

This article reviews the history, the present status and possible future developments of HgCdTe ternary alloy for infrared (IR) detector applications. HgCdTe IR detectors have been intensively developed since the first synthesis of this material in 1958. This article summarizes the fundamental properties of this versatile narrow gap semiconductor, and relates the material properties to its successful applications as an IR photoconductive and photovoltaic detector material. An emphasis is put on key developments in the crystal growth and their influence on device evolution. Competitive technologies to HgCdTe ternary alloy are also presented. Recent advances of backside illuminated HgCdTe heterojunction photodiodes have enabled a third generation of multispectral instruments for remote sensing applications and have led to the practicality of multiband IR focal plane array technology. Finally, evaluation of HgCdTe for room temperature long wavelength IR applications is presented. (Some figures in this article are in colour only in the electronic version)

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HgCdTe infrared detector material: history, status and outlook

Infrared detectors: an overview

This survey deals with 1/f noise in homogeneous semiconductor samples. A distinction is made between mobility noise and number noise. It is shown that there always is mobility noise with an /spl alpha/ value with a magnitude in the order of 10/sup -4/. Damaging the crystal has a strong influence on /spl alpha/, /spl alpha/ may increase by orders of magnitude. Some theoretical models are briefly discussed none of them can explain all experimental results. The /spl alpha/ values of several semiconductors are given. These values can be used in calculations of 1/f noise in devices. >

1/f Noise Sources

Ultimate performance of infrared photodetectors and figure of merit of detector material

https://gendocs.ru/docs/40/39170/conv_1/file1.pdf

Progress in MOCVD growth of HgCdTe heterostructures for uncooled infrared photodetectors

The article presents state of work in technology of free-space optical communications (Free Space Optics − FSO). Both commercially available optical data links and their further development are described. The main elements and operation limiting factors of FSO systems have been identified. Additionally, analyses of FSO/RF hybrid systems application are included. The main aspects of LasBITer project related to such hybrid technology for security and defence applications are presented.

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Analysis of Free-Space Optics Development

The major drawback of IR photodetectors is the need for cooling to suppress thermal generation of free carriers resulting in noise. New ways to improve the performance of infrared photodetectors operated without cryogenical cooling are discussed, including the optimum design of the devices, the use of optical immersion of photodetectors to high refraction index lenses, and the optical resonant cavity. Another and very promising way, however, is the suppression of thermal generation, which is governed by the Auger mechanism by depletion of the semiconductor in charge carriers. The stationary depletion can be achieved by the use of exclusion, extraction, and magnetoconcentration effects. The combination of various methods would eventually enable us to achieve near-background-limited photodetection (near-BLIP) performance of IR detectors without cooling.

New generation of near-room-temperature photodetectors

This paper reports on the unipolar medium wavelength infrared (MWIR) InAs/GaSb/B?Al0.2Ga0.8Sb type-II superlattice (T2SL) nBn detector's photoelectrical performance. In our model, the heterojunction barrier-active region (absorber) was assumed to be decisive as the contributing dark current mechanism limiting nBn's detector performance. The voltage drop analysis on the nBn structure was introduced to estimate the bias drop on the heterojunction barrier-active region. It was assumed that the contact n+-barrier heterojunction's layer has an insignificant influence on the electrical properties of the detector. In addition, a bulk-based model with an effective band gap of T2SL material has been assumed in the device modeling. Both current?voltage (I?V) and differential resistance?area product RA(V,T), characteristics of nBn's detector were found to be dominated by diffusion and generation?recombination currents in the zero-bias and the low-bias regions. At medium values of reverse voltages, the dark current was mostly affected by trap-assisted tunneling, whereas the band-to-band tunneling revealed its contribution at high values of reverse bias (V > 0.7?V). The RA(V,T) characteristics' fitting procedure allowed estimation of both diffusion and generation?recombination lifetimes as well as the trap energy level temperature dependence within T2SL energy gap. It was predicted that at T = 77 K, the RA product and detectivity reached values of 1000 ?cm2?and 4???1011?cm Hz1/2?W-1, respectively. The corresponding values at room temperature were 0.01 ?cm2?and D* = 5???108?cmHz1/2?W?1, respectively. Finally, InAs/GaSb/B?Al0.2Ga0.8Sb T2SLs nBn's state of the art was compared to the performance of InAs/GaSb T2SLs PIN photodiodes and the HgCdTe bulk photodiodes operated at near-room temperature. It was shown that the RA product of the MWIR T2SLs nBn detector has reached a comparable level with the state of the art of the HgCdTe bulk photodiodes.

Waldemar Gawron

Papers

Ultimate performance of infrared photodetectors and figure of merit of detector material

Progress in MOCVD growth of HgCdTe heterostructures for uncooled infrared photodetectors

Analysis of Free-Space Optics Development

New generation of near-room-temperature photodetectors

Performance modeling of MWIR InAs/GaSb/B–Al0.2Ga0.8Sb type-II superlattice nBn detector