{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T05:06:04Z","timestamp":1787029564115,"version":"3.56.0"},"reference-count":35,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2023,3,31]],"date-time":"2023-03-31T00:00:00Z","timestamp":1680220800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"UNIQUE","award":["ERC-COG-863487"],"award-info":[{"award-number":["ERC-COG-863487"]}]},{"name":"UNIQUE","award":["EP\/P021859\/1"],"award-info":[{"award-number":["EP\/P021859\/1"]}]},{"name":"UNIQUE","award":["EP\/W028921\/1"],"award-info":[{"award-number":["EP\/W028921\/1"]}]},{"name":"EPSRC (UK)","award":["ERC-COG-863487"],"award-info":[{"award-number":["ERC-COG-863487"]}]},{"name":"EPSRC (UK)","award":["EP\/P021859\/1"],"award-info":[{"award-number":["EP\/P021859\/1"]}]},{"name":"EPSRC (UK)","award":["EP\/W028921\/1"],"award-info":[{"award-number":["EP\/W028921\/1"]}]},{"name":"TeraCom","award":["ERC-COG-863487"],"award-info":[{"award-number":["ERC-COG-863487"]}]},{"name":"TeraCom","award":["EP\/P021859\/1"],"award-info":[{"award-number":["EP\/P021859\/1"]}]},{"name":"TeraCom","award":["EP\/W028921\/1"],"award-info":[{"award-number":["EP\/W028921\/1"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Charge-sensitive infrared photo-transistors (CSIP) are quantum detectors of mid-infrared radiation (\u03bb=4\u00a0\u00b5m\u221214\u00a0\u00b5m) which have been reported to have outstanding figures of merit and sensitivities that allow single photon detection. The typical absorbing region of a CSIP consists of an AlxGa1-xAs quantum heterostructure, where a GaAs quantum well, where the absorption takes place, is followed by a triangular barrier with a graded x(Al) composition that connects the quantum well to a source-drain channel. Here, we report a CSIP designed to work for a 9.3 \u00b5m wavelength where the Al composition is kept constant and the triangular barrier is replaced by tunnel-coupled quantum wells. This design is thus conceptually closer to quantum cascade detectors (QCDs) which are an established technology for detection in the mid-infrared range. While previously reported structures use metal gratings in order to couple infrared radiation in the absorbing quantum well, here, we employ a 45\u00b0 wedge facet coupling geometry that allows a simplified and reliable estimation of the incident photon flux \u03a6 in the device. Remarkably, these detectors have an \u201cauto-calibrated\u201d nature, which enables the precise assessment of the photon flux \u03a6 solely by measuring the electrical characteristics and from knowledge of the device geometry. We identify an operation regime where CSIP detectors can be directly compared to other unipolar quantum detectors such as quantum well infrared photodetectors (QWIPs) and QCDs and we estimate the corresponding detector figure of merit under cryogenic conditions. The maximum responsivity R = 720 A\/W and a photoconductive gain G~2.7 \u00d7 104 were measured, and were an order of magnitude larger than those for QCDs and quantum well infrared photodetectors (QWIPs). We also comment on the benefit of nano-antenna concepts to increase the efficiency of CSIP in the photon-counting regime.<\/jats:p>","DOI":"10.3390\/s23073635","type":"journal-article","created":{"date-parts":[[2023,3,31]],"date-time":"2023-03-31T08:27:27Z","timestamp":1680251247000},"page":"3635","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Auto-Calibrated Charge-Sensitive Infrared Phototransistor at 9.3 \u00b5m"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-1142-6050","authenticated-orcid":false,"given":"Mohsen","family":"Bahrehmand","sequence":"first","affiliation":[{"name":"Laboratoire de Physique de l\u2019Ecole Normale Sup\u00e9rieure, Ecole Normale Sup\u00e9rieure, Paris Sciences et Lettres, Centre National de la Recherche Scientifique (CNRS), Universit\u00e9 de Paris, 24 Rue Lhomond, 75005 Paris, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0334-1815","authenticated-orcid":false,"given":"Djamal","family":"Gacemi","sequence":"additional","affiliation":[{"name":"Laboratoire de Physique de l\u2019Ecole Normale Sup\u00e9rieure, Ecole Normale Sup\u00e9rieure, Paris Sciences et Lettres, Centre National de la Recherche Scientifique (CNRS), Universit\u00e9 de Paris, 24 Rue Lhomond, 75005 Paris, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Angela","family":"Vasanelli","sequence":"additional","affiliation":[{"name":"Laboratoire de Physique de l\u2019Ecole Normale Sup\u00e9rieure, Ecole Normale Sup\u00e9rieure, Paris Sciences et Lettres, Centre National de la Recherche Scientifique (CNRS), Universit\u00e9 de Paris, 24 Rue Lhomond, 75005 Paris, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lianhe","family":"Li","sequence":"additional","affiliation":[{"name":"School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alexander Giles","family":"Davies","sequence":"additional","affiliation":[{"name":"School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Edmund","family":"Linfield","sequence":"additional","affiliation":[{"name":"School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1817-4554","authenticated-orcid":false,"given":"Carlo","family":"Sirtori","sequence":"additional","affiliation":[{"name":"Laboratoire de Physique de l\u2019Ecole Normale Sup\u00e9rieure, Ecole Normale Sup\u00e9rieure, Paris Sciences et Lettres, Centre National de la Recherche Scientifique (CNRS), Universit\u00e9 de Paris, 24 Rue Lhomond, 75005 Paris, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yanko","family":"Todorov","sequence":"additional","affiliation":[{"name":"Laboratoire de Physique de l\u2019Ecole Normale Sup\u00e9rieure, Ecole Normale Sup\u00e9rieure, Paris Sciences et Lettres, Centre National de la Recherche Scientifique (CNRS), Universit\u00e9 de Paris, 24 Rue Lhomond, 75005 Paris, France"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,3,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"851","DOI":"10.1063\/1.102682","article-title":"High Sensitivity Low Dark Current 10 \u039cm GaAs Quantum Well Infrared Photodetectors","volume":"56","author":"Levine","year":"1990","journal-title":"Appl. Phys. Lett."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2824","DOI":"10.1063\/1.1781731","article-title":"Quantum Cascade Photodetector","volume":"85","author":"Gendron","year":"2004","journal-title":"Appl. Phys. Lett."},{"key":"ref_3","unstructured":"Tourni\u00e9, E., and Cerutti, L. (2020). Mid-Infrared Optoelectronics, Woodhead Publishing."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1016\/S1350-4495(02)00140-8","article-title":"Infrared Detectors: An Overview","volume":"43","author":"Rogalski","year":"2002","journal-title":"Infrared Phys. Technol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1016\/S0079-6727(02)00024-1","article-title":"Infrared Detectors: Status and Trends","volume":"27","author":"Rogalski","year":"2003","journal-title":"Prog. Quantum Electron."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"553","DOI":"10.1126\/science.264.5158.553","article-title":"Quantum Cascade Laser","volume":"264","author":"Faist","year":"1994","journal-title":"Science"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Rosencher, E., and Vinter, B. (2002). Optoelectronics, Cambridge University Press.","DOI":"10.1017\/CBO9780511754647"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1507","DOI":"10.1063\/1.107286","article-title":"Photoconductive Gain Mechanism of Quantum-well Intersubband Infrared Detectors","volume":"60","author":"Liu","year":"1992","journal-title":"Appl. Phys. Lett."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"172106","DOI":"10.1063\/1.1920425","article-title":"Infrared Phototransistor Using Capacitively Coupled Two-Dimensional Electron Gas Layers","volume":"86","author":"An","year":"2005","journal-title":"Appl. Phys. Lett."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"8411","DOI":"10.3390\/s100908411","article-title":"Novel Ultra-Sensitive Detectors in the 10\u201350 \u039cm Wavelength Range","volume":"10","author":"Ueda","year":"2010","journal-title":"Sensors"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"064517","DOI":"10.1063\/1.3087579","article-title":"Temperature Dependence of the Performance of Charge-Sensitive Infrared Phototransistors","volume":"105","author":"Ueda","year":"2009","journal-title":"J. Appl. Phys."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Grabert, H., and Devoret, M.H. (1992). Single Charge Tunneling, Springer.","DOI":"10.1007\/978-1-4757-2166-9"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Sze, S.M., and Ng, K.K. (2006). Physics of Semiconductor Devices, John Wiley & Sons.","DOI":"10.1002\/0470068329"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"093109","DOI":"10.1063\/1.2919779","article-title":"Charge-Sensitive Infrared Phototransistors: Characterization by an All-Cryogenic Spectrometer","volume":"103","author":"Ueda","year":"2008","journal-title":"J. Appl. Phys."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"085417","DOI":"10.1103\/PhysRevB.75.085417","article-title":"Metastable Excited States of a Closed Quantum Dot with High Sensitivity to Infrared Photons","volume":"75","author":"An","year":"2007","journal-title":"Phys. Rev. B"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"063702","DOI":"10.1063\/1.3152224","article-title":"A Passive Long-Wavelength Infrared Microscope with a Highly Sensitive Phototransistor","volume":"80","author":"Kajihara","year":"2009","journal-title":"Rev. Sci. Instrum."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"033706","DOI":"10.1063\/1.3360826","article-title":"A Sensitive Near-Field Microscope for Thermal Radiation","volume":"81","author":"Kajihara","year":"2010","journal-title":"Rev. Sci. Instrum."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"023701","DOI":"10.1063\/5.0133575","article-title":"Development of a Cryogenic Passive-Scattering-Type near-Field Optical Microscopy System","volume":"94","author":"Lin","year":"2023","journal-title":"Rev. Sci. Instrum."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"775","DOI":"10.1126\/science.aam9991","article-title":"Imaging of Nonlocal Hot-Electron Energy Dissipation via Shot Noise","volume":"360","author":"Weng","year":"2018","journal-title":"Science"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"4752","DOI":"10.1038\/s41467-021-25094-5","article-title":"Quasiadiabatic Electron Transport in Room Temperature Nanoelectronic Devices Induced by Hot-Phonon Bottleneck","volume":"12","author":"Weng","year":"2021","journal-title":"Nat. Commun."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"4220","DOI":"10.1021\/acs.nanolett.8b01178","article-title":"Near-Field Radiative Nanothermal Imaging of Nonuniform Joule Heating in Narrow Metal Wires","volume":"18","author":"Weng","year":"2018","journal-title":"Nano Lett."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"096501","DOI":"10.35848\/1882-0786\/abae0a","article-title":"Nanoscale Probing of Thermally Excited Evanescent Fields in an Electrically Biased Graphene by Near-Field Optical Microscopy","volume":"13","author":"Lin","year":"2020","journal-title":"Appl. Phys. Express"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"091102","DOI":"10.1063\/1.4961938","article-title":"Highly Photoresponsive Charge-Sensitive Infrared Phototransistors with a Dynamically Controlled Optical Gate","volume":"109","author":"Xu","year":"2016","journal-title":"Appl. Phys. Lett."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"233501","DOI":"10.1063\/5.0007724","article-title":"Linear Array of Charge Sensitive Infrared Phototransistors for Long Wavelength Infrared Detection","volume":"116","author":"Wang","year":"2020","journal-title":"Appl. Phys. Lett."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1142\/9789813223288_0011","article-title":"Improved Performance of Ultrahigh-Sensitive Charge-Sensitive Infrared Phototransistors (CSIP)","volume":"Volume 58","author":"Kim","year":"2017","journal-title":"Fundamental and Applied Problems of Terahertz Devices and Technologies"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"103505","DOI":"10.1063\/5.0059399","article-title":"Dual-Color Charge-Sensitive Infrared Phototransistors with Dynamic Optical Gate","volume":"119","author":"Xu","year":"2021","journal-title":"Appl. Phys. Lett."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/S0080-8784(08)60304-X","article-title":"Chapter 1 The Basic Physics of Intersubband Transitions","volume":"Volume 62","author":"Liu","year":"1999","journal-title":"Semiconductors and Semimetals"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"4430","DOI":"10.1021\/acs.nanolett.0c01217","article-title":"Absorption Engineering in an Ultrasubwavelength Quantum System","volume":"20","author":"Jeannin","year":"2020","journal-title":"Nano Lett."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"935","DOI":"10.1007\/s11468-014-9699-y","article-title":"Maximizing Absorption and Scattering by Dipole Particles","volume":"9","author":"Tretyakov","year":"2014","journal-title":"Plasmonics"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Loudon, R. (2000). The Quantum Theory of Light, OUP.","DOI":"10.1093\/oso\/9780198501770.001.0001"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1038\/nature25790","article-title":"Room-Temperature Nine-\u039cm-Wavelength Photodetectors and GHz-Frequency Heterodyne Receivers","volume":"556","author":"Palaferri","year":"2018","journal-title":"Nature"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"251102","DOI":"10.1063\/5.0033367","article-title":"High Temperature Metamaterial Terahertz Quantum Detector","volume":"117","author":"Jeannin","year":"2020","journal-title":"Appl. Phys. Lett."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Bigioli, A., Gacemi, D., Palaferri, D., Todorov, Y., Vasanelli, A., Suffit, S., Li, L., Davies, A.G., Linfield, E.H., and Kapsalidis, F. (2020). Mixing Properties of Room Temperature Patch-Antenna Receivers in a Mid-Infrared (\u03bb \u2248 9 \u039cm) Heterodyne System. Laser Photonics Rev., 14.","DOI":"10.1002\/lpor.201900207"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"4753","DOI":"10.1038\/s41467-022-32417-7","article-title":"A Mid-Infrared Lab-on-a-Chip for Dynamic Reaction Monitoring","volume":"13","author":"Hinkov","year":"2022","journal-title":"Nat. Commun."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1146\/annurev-anchem-071015-041507","article-title":"Advances in Mid-Infrared Spectroscopy for Chemical Analysis","volume":"9","author":"Haas","year":"2016","journal-title":"Annu. Rev. Anal. Chem."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/7\/3635\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T19:08:02Z","timestamp":1760123282000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/7\/3635"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,3,31]]},"references-count":35,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2023,4]]}},"alternative-id":["s23073635"],"URL":"https:\/\/doi.org\/10.3390\/s23073635","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,3,31]]}}}