narrow-gap semiconductor

{{Short description|All semiconductors with bandgaps smaller than silicon}}

Narrow-gap semiconductors are semiconducting materials with a magnitude of bandgap that is smaller than 0.7 eV, which corresponds to an infrared absorption cut-off wavelength over 2.5 micron. A more extended definition includes all semiconductors with bandgaps smaller than silicon (1.1 eV).{{cite journal|title=Narrow-Bandgap Materials for Optoelectronics Applications|first1=Xiao-Hui|last1=Li|date=2022|doi=10.1007/s11467-021-1055-z|url=https://link.springer.com/article/10.1007/s11467-021-1055-z|volume=17|pages=13304|journal=Frontiers of Physics|issue=1 |bibcode=2022FrPhy..1713304L |s2cid=237652629 |url-access=subscription}}{{cite book|title=Physics and Properties of Narrow Gap Semiconductors|url=https://link.springer.com/book/10.1007/978-0-387-74801-6|first1=Junhao|last1=Chu|first2=Arden|last2=Sher|date=2008 |publisher=Springer|doi=10.1007/978-0-387-74801-6 | isbn=978-0-387-74743-9}} Modern terahertz,{{cite book

|author1=Jones, Graham A.|author2=Layer, David H.|author3=Osenkowsky, Thomas G.|year=2007|title=National Association of Broadcasters Engineering Handbook

|page=7|publisher=Taylor and Francis|isbn=978-1-136-03410-7|url=https://books.google.com/books?id=K9N1TVhf82YC&pg=PA7}} infrared,{{cite journal|journal=Micromachines|year=2022|first1=M.|last1=Avraham|first2=J.|last2=Nemirovsky|first3=T.|last3=Blank|first4=G.|last4=Golan|first5=Y.|last5=Nemirovsky|title=Toward an Accurate IR Remote Sensing of Body Temperature Radiometer Based on a Novel IR Sensing System Dubbed Digital TMOS|volume = 13|number = 5|page=703 |doi = 10.3390/mi13050703|pmid=35630174 |pmc=9145132 |doi-access=free}} and thermographic{{cite book| first = Bruce | last = Hapke | name-list-style = vanc |title=Theory of Reflectance and Emittance Spectroscopy |url=https://books.google.com/books?id=3FNzaFuoXY0C|date=19 January 2012 |publisher=Cambridge University Press|isbn=978-0-521-88349-8 |page=416}} technologies are all based on this class of semiconductors.

Narrow-gap materials made it possible to realize satellite remote sensing,Lovett, D. R. Semimetals and narrow-bandgap semiconductors; Pion Limited: London, 1977; Chapter 7. photonic integrated circuits for telecommunications,{{Cite news |last=Inside Telecom Staff |date=30 July 2022 |title=How Can Photonic Chips Help to Create a Sustainable Digital Infrastructure? |work=Inside Telecom |url=https://insidetelecom.com/how-can-photonic-chips-help-to-create-a-sustainable-digital-infrastructure/ |access-date=20 September 2022}}{{cite journal |last1=Awad |first1=Ehab |title=Bidirectional Mode Slicing and Re-Combining for Mode Conversion in Planar Waveguides |journal=IEEE Access |date=October 2018 |volume=6 |issue=1 |page=55937 |doi=10.1109/ACCESS.2018.2873278 |s2cid=53043619 |ref=12|doi-access=free }}{{Cite news |last=Vergyris |first=Panagiotis |date=16 June 2022 |title=Integrated photonics for quantum applications |work=Laser Focus World |url=https://www.laserfocusworld.com/optics/article/14282714/integrated-photonics-for-quantum-applications |access-date=20 September 2022}} and unmanned vehicle Li-Fi systems,{{Cite web|url=https://www.lifi.eng.ed.ac.uk/lifi-news/2017-04-01-1855/comprehensive-summary-modulation-techniques-lifi|title=Comprehensive Summary of Modulation Techniques for LiFi {{!}} LiFi Research|website=www.lifi.eng.ed.ac.uk|access-date=2018-01-16}} in the regime of Infrared detector and thermography.{{cite web |url=http://www.spitzer.caltech.edu/mission/398-The-Infrared-Array-Camera-IRAC- |title=The Infrared Array Camera (IRAC) |series=Spitzer Space Telescope |publisher=NASA{{\}}JPL{{\}}Caltech |accessdate=13 January 2017 |archive-date=13 June 2010 |archive-url=https://web.archive.org/web/20100613233239/http://spitzer.caltech.edu/mission/398-The-Infrared-Array-Camera-IRAC- |url-status=dead }}{{cite news |url=http://newatlas.com/spitzer-beyond/45123/ |title=Spitzer goes "Beyond" for final mission |work=New Atlas |first=David |last=Szondy |date=28 August 2016 |accessdate=13 January 2017}} They are also the materials basis for terahertz technology, including security surveillance of concealed weapon uncovering,[http://www.esa.int/spaceinimages/Images/2002/06/Meeting_the_team "Space in Images – 2002–06 – Meeting the team"].{{Cite web |date=2003-02-12 |title=Space camera blazes new terahertz trails |url=https://www.timeshighereducation.com/news/space-camera-blazes-new-terahertz-trails/174657.article |access-date=2023-08-04 |website=Times Higher Education (THE) |language=en}}[https://web.archive.org/web/20140315232115/http://www.epsrc.ac.uk/newsevents/news/2004/Pages/rcukbusinessplan.aspx Winner of the 2003/04 Research Councils' Business Plan Competition – 24 February 2004]. epsrc.ac.uk. 27 February 2004 safe medical and industrial imaging with terahertz tomography,{{Cite journal | doi=10.1007/s10762-014-0057-0|title = Review of Terahertz Tomography Techniques| journal=Journal of Infrared, Millimeter, and Terahertz Waves| volume=35| issue=4| pages=382–411|year = 2014|last1 = Guillet|first1 = J. P.| last2=Recur| first2=B.| last3=Frederique| first3=L.| last4=Bousquet| first4=B.| last5=Canioni| first5=L.| last6=Manek-Hönninger| first6=I.| last7=Desbarats| first7=P.| last8=Mounaix| first8=P.| bibcode=2014JIMTW..35..382G | citeseerx=10.1.1.480.4173| s2cid=120535020 }}{{Cite journal |last1=Mittleman |first1=Daniel M. |last2=Hunsche |first2=Stefan |last3=Boivin |first3=Luc |last4=Nuss |first4=Martin C. |date=1997 |title=T-ray tomography |url=https://opg.optica.org/ol/abstract.cfm?uri=ol-22-12-904 |journal=Optics Letters |language=EN |volume=22 |issue=12 |pages=904–906 |doi=10.1364/OL.22.000904 |pmid=18185701 |bibcode=1997OptL...22..904M |issn=1539-4794|url-access=subscription }}{{Cite journal |last1=Katayama |first1=I. |last2=Akai |first2=R. |last3=Bito |first3=M. |last4=Shimosato |first4=H. |last5=Miyamoto |first5=K. |last6=Ito |first6=H. |last7=Ashida |first7=M. |date=2010 |title=Ultrabroadband terahertz generation using 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate single crystals |url=https://pubs.aip.org/apl/article/97/2/021105/339188/Ultrabroadband-terahertz-generation-using-4-N-N |journal=Applied Physics Letters |language=en |volume=97 |issue=2 |page=021105 |doi=10.1063/1.3463452 |bibcode=2010ApPhL..97b1105K |issn=0003-6951|url-access=subscription }} as well as dielectric wakefield accelerators.{{cite journal | last1=Dolgashev | first1=Valery| last2=Tantawi | first2=Sami| last3=Higashi | first3=Yasuo | last4=Spataro | first4=Bruno| date=2010-10-25 | title=Geometric dependence of radio-frequency breakdown in normal conducting accelerating structures | journal=Applied Physics Letters | volume=97 | issue=17 | page=171501 | doi=10.1063/1.3505339| bibcode=2010ApPhL..97q1501D}}{{cite journal | last1=Nanni | first1=Emilio A. | last2=Huang | first2=Wenqian R.| last3=Hong | first3=Kyung-Han | last4=Ravi | first4=Koustuban | last5=Fallahi | first5=Arya | last6=Moriena | first6=Gustavo | last7=Dwayne Miller | first7=R. J. | last8=Kärtner | first8=Franz X. | date=2015-10-06 | title=Terahertz-driven linear electron acceleration| journal=Nature Communications | volume=6 | issue=1 | page=8486 | doi=10.1038/ncomms9486 | pmid=26439410 | pmc=4600735 | arxiv=1411.4709 | bibcode=2015NatCo...6.8486N }}{{cite journal| last=Jing | first=Chunguang | year=2016 | title=Dielectric Wakefield Accelerators| journal=Reviews of Accelerator Science and Technology | volume=09 | issue=6 | pages=127–149| doi=10.1142/s1793626816300061 | bibcode=2016RvAST...9..127J }} Besides, thermophotovoltaics embedded with narrow-gap semiconductors can potentially use the traditionally wasted portion of solar energy that takes up ~49% of the sun light spectrum.{{cite web |last=Poortmans |first=Jef |title=IMEC website: Photovoltaic Stacks |url=http://www.imec.be/wwwinter/energy/space_main.shtml |archive-url=https://web.archive.org/web/20071013061056/http://www.imec.be/wwwinter/energy/space_main.shtml |archive-date=2007-10-13 |access-date=2008-02-17}}{{Cite web |title=A new heat engine with no moving parts is as efficient as a steam turbine |url=https://news.mit.edu/2022/thermal-heat-engine-0413 |access-date=2022-04-13 |website=MIT News {{!}} Massachusetts Institute of Technology |date=13 April 2022 |language=en}} Spacecraft, deep ocean instruments, and vacuum physics setups use narrow-gap semiconductors to achieve cryogenic cooling.{{Cite journal |last=Radebaugh |first=Ray |date=2009-03-31 |title=Cryocoolers: the state of the art and recent developments |url=https://doi.org/10.1088/0953-8984/21/16/164219 |journal=Journal of Physics: Condensed Matter |language=en |volume=21 |issue=16 |page=164219 |bibcode=2009JPCM...21p4219R |doi=10.1088/0953-8984/21/16/164219 |issn=0953-8984 |pmid=21825399 |s2cid=22695540|url-access=subscription }}{{Cite journal |last1=Cooper |first1=Bernard E |last2=Hadfield |first2=Robert H |date=2022-06-28 |title=Viewpoint: Compact cryogenics for superconducting photon detectors |url=https://doi.org/10.1088/1361-6668/ac76e9 |journal=Superconductor Science and Technology |language=en |volume=35 |issue=8 |page=080501 |bibcode=2022SuScT..35h0501C |doi=10.1088/1361-6668/ac76e9 |issn=0953-2048 |s2cid=249534834|doi-access=free }}