{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T02:12:26Z","timestamp":1781662346387,"version":"3.54.5"},"reference-count":26,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2021,1,17]],"date-time":"2021-01-17T00:00:00Z","timestamp":1610841600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000001","name":"National science foundation","doi-asserted-by":"publisher","award":["ECCS1840712"],"award-info":[{"award-number":["ECCS1840712"]}],"id":[{"id":"10.13039\/100000001","id-type":"DOI","asserted-by":"publisher"}]},{"name":"N5 Sensors Inc.","award":["Internal Funding"],"award-info":[{"award-number":["Internal Funding"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this work, a TiO2-coated GaN nanowire-based back-gate field-effect transistor (FET) device was designed and implemented to address the well-known cross-sensitive nature of metal oxides. Even though a two-terminal TiO2\/GaN chemiresistor is highly sensitive to NO2, it suffers from lack of selectivity toward NO2 and SO2. Here, a Si back gate with C-AlGaN as the gate dielectric was demonstrated as a tunable parameter, which enhances discrimination of these cross-sensitive gases at room temperature (20 \u00b0C). Compared to no bias, a back-gate bias resulted in a significant 60% increase in NO2 response, whereas the increase was an insignificant 10% in SO2 response. The differential change in gas response was explained with the help of a band diagram, derived from the energetics of molecular models based on density functional theory (DFT). The device geometries in this work are not optimized and are intended only for proving the concept.<\/jats:p>","DOI":"10.3390\/s21020624","type":"journal-article","created":{"date-parts":[[2021,1,20]],"date-time":"2021-01-20T03:34:25Z","timestamp":1611113665000},"page":"624","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["Back-Gate GaN Nanowire-Based FET Device for Enhancing Gas Selectivity at Room Temperature"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0070-8872","authenticated-orcid":false,"given":"Md Ashfaque Hossain","family":"Khan","sequence":"first","affiliation":[{"name":"Department of Electrical and Computer Engineering, George Mason University, Fairfax, VA 22030, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ratan","family":"Debnath","sequence":"additional","affiliation":[{"name":"N5 Sensors, Inc., Rockville, MD 20850, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Abhishek","family":"Motayed","sequence":"additional","affiliation":[{"name":"N5 Sensors, Inc., Rockville, MD 20850, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mulpuri V.","family":"Rao","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, George Mason University, Fairfax, VA 22030, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,1,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Khan, M.A.H., Rao, M.V., and Li, Q. (2019). Recent Advances in Electrochemical Sensors for Detecting Toxic Gases: NO2, SO2 and H2S. Sensors, 19.","DOI":"10.3390\/s19040905"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"4523","DOI":"10.1021\/jp9706994","article-title":"Dynamics of Gas\u2212Surface Interactions: Reaction of Atomic Oxygen with Chemisorbed Hydrogen on Tungsten","volume":"101","author":"Ree","year":"1997","journal-title":"J. Phys. Chem. A"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"206","DOI":"10.1016\/j.mseb.2017.12.036","article-title":"Semiconductor metal oxide gas sensors: A review","volume":"229","author":"Dey","year":"2018","journal-title":"Mater. Sci. Eng. B"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1973","DOI":"10.1002\/2013JD020485","article-title":"Emission measurements of alkenes, alkanes, SO2, and NO2 from stationary sources in Southeast Texas over a 5 year period using SOF and mobile DOAS","volume":"119","author":"Johansson","year":"2014","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2610","DOI":"10.3390\/s120302610","article-title":"Metal Oxide Nanostructures and Their Gas Sensing Properties: A Review","volume":"12","author":"Sun","year":"2012","journal-title":"Sensors"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"6020","DOI":"10.1109\/JSEN.2020.2972542","article-title":"Nanowire-Based Sensor Array for Detection of Cross-Sensitive Gases Using PCA and Machine Learning Algorithms","volume":"20","author":"Khan","year":"2020","journal-title":"IEEE Sens. J."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Khan, M.A.H., Motayed, A., and Rao, M.V. (2020). Identification and quantification of gases and their mixtures using GaN sensor array and artificial neural network. Meas. Sci. Technol.","DOI":"10.1088\/1361-6501\/abd5f0"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Rani, A., DiCamillo, K., Khan, M.A.H., Paranjape, M., and E Zaghloul, M. (2019). Tuning the Polarity of MoTe2 FETs by Varying the Channel Thickness for Gas-Sensing Applications. Sensors, 19.","DOI":"10.3390\/s19112551"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Khan, M.A.H., and Rao, M.V. (2020). Gallium Nitride (GaN) Nanostructures and Their Gas Sensing Properties: A Review. Sensors, 20.","DOI":"10.3390\/s20143889"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Wang, Z.L. (2006). Novel Nanostructures and Nanodevices of ZnO. Zinc Oxide Bulk, Thin Films and Nanostructures, Elsevier.","DOI":"10.1016\/B978-008044722-3\/50010-5"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"178","DOI":"10.1016\/j.snb.2012.10.134","article-title":"Nanowire-based gas sensors","volume":"177","author":"Chen","year":"2013","journal-title":"Sens. Actuators B Chem."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1007\/s40820-014-0023-3","article-title":"Zinc Oxide Nanostructures for NO2 Gas\u2013Sensor Applications: A Review","volume":"7","author":"Kumar","year":"2015","journal-title":"Nano-Micro Lett."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"095508","DOI":"10.1088\/0957-4484\/19\/9\/095508","article-title":"Novel fabrication of an SnO2nanowire gas sensor with high sensitivity","volume":"19","author":"Choi","year":"2008","journal-title":"Nanotechnology"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"295503","DOI":"10.1088\/0957-4484\/22\/29\/295503","article-title":"Highly selective GaN-nanowire\/TiO2-nanocluster hybrid sensors for detection of benzene and related environment pollutants","volume":"22","author":"Aluri","year":"2011","journal-title":"Nanotechnology"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1883","DOI":"10.1109\/JSEN.2013.2241423","article-title":"Nitro-Aromatic Explosive Sensing Using GaN Nanowire-Titania Nanocluster Hybrids","volume":"13","author":"Aluri","year":"2013","journal-title":"IEEE Sens. J."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"121602","DOI":"10.1063\/1.5116677","article-title":"High-performance room-temperature TiO2-functionalized GaN nanowire gas sensors","volume":"115","author":"Shi","year":"2019","journal-title":"Appl. Phys. Lett."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"155504","DOI":"10.1088\/1361-6528\/ab6685","article-title":"Reliable anatase-titania nanoclusters functionalized GaN sensor devices for UV assisted NO2 gas-sensing in ppb level","volume":"31","author":"Khan","year":"2020","journal-title":"Nanotechnology"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"128223","DOI":"10.1016\/j.snb.2020.128223","article-title":"Scalable metal oxide functionalized GaN nanowire for precise SO2 detection","volume":"318","author":"Khan","year":"2020","journal-title":"Sens. Actuators B Chem."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"742","DOI":"10.1109\/TDMR.2020.3028786","article-title":"Accelerated Stress Tests and Statistical Reliability Analysis of Metal-Oxide\/GaN Nanostructured Sensor Devices","volume":"20","author":"Khan","year":"2020","journal-title":"IEEE Trans. Device Mater. Reliab."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"175501","DOI":"10.1088\/0957-4484\/23\/17\/175501","article-title":"Methanol, ethanol and hydrogen sensing using metal oxide and metal (TiO2\u2013Pt) composite nanoclusters on GaN nanowires: A new route towards tailoring the selectivity of nanowire\/nanocluster chemical sensors","volume":"23","author":"Aluri","year":"2012","journal-title":"Nanotechnology"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"630","DOI":"10.1126\/science.291.5504.630","article-title":"Directed Assembly of One-Dimensional Nanostructures into Functional Networks","volume":"291","author":"Huang","year":"2001","journal-title":"Science"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"114310","DOI":"10.1063\/1.2397383","article-title":"Realization of reliable GaN nanowire transistors utilizing dielectrophoretic alignment technique","volume":"100","author":"Motayed","year":"2006","journal-title":"J. Appl. Phys."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"7138","DOI":"10.1109\/JSEN.2020.2978221","article-title":"Functionalization of GaN Nanowire Sensors With Metal Oxides: An Experimental and DFT Investigation","volume":"20","author":"Khan","year":"2020","journal-title":"IEEE Sens. J."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Khan, M.A.H., Thomson, B., Motayed, A., Li, Q., and Rao, M.V. (2020). Metal-oxide\/GaN based NO2 Gas detection at room temperature: An experimental and density functional theory investigation. Micro- and Nanotechnology Sensors, Systems, and Applications XII, SPIE.","DOI":"10.1117\/12.2557971"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"20666","DOI":"10.1039\/C7TA07001B","article-title":"Room-temperature SO2 gas-sensing properties based on a metal-doped MoS2 nanoflower: An experimental and density functional theory investigation","volume":"5","author":"Zhang","year":"2017","journal-title":"J. Mater. Chem. A"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"045403","DOI":"10.1088\/1361-6404\/aa6a0d","article-title":"Quantum and classical limits in a potential step","volume":"38","author":"Dib","year":"2017","journal-title":"Eur. J. Phys."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/2\/624\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:12:12Z","timestamp":1760159532000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/2\/624"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,1,17]]},"references-count":26,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2021,1]]}},"alternative-id":["s21020624"],"URL":"https:\/\/doi.org\/10.3390\/s21020624","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,1,17]]}}}