Enhanced detection of NO2 with recessed AlGaN/GaN open gate structures

Vitushinsky, R.; Crego‐Calama, Mercedes; Brongersma, Sywert; Offermans, P.

doi:10.1063/1.4803001

Cited by 21 publications

(14 citation statements)

References 32 publications

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“…In this latter mode of operation UV photo-activation has also been shown to be effective [8,9,10,11,12,13]. A second group of materials that exhibits a similar kind of low-temperature response, is III-nitride materials both in the form of AlGaN/GaN high electron mobility transistors (HEMT) with flat surface morphologies [14,15,16,17,18,19] as well as in the form of GaN/InGaN nanowire heterostructures [20,21,22]. These effects can be attributed to the fact that III-nitride surfaces tend to develop surface oxides when exposed to ambient air which makes them similar to conventional MOx materials [23,24,25,26,27,28].…”

Section: Introductionmentioning

confidence: 99%

Effect of Water Vapor and Surface Morphology on the Low Temperature Response of Metal Oxide Semiconductor Gas Sensors

et al. 2015

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In this work the low temperature response of metal oxide semiconductor gas sensors is analyzed. Important characteristics of this low-temperature response are a pronounced selectivity to acid- and base-forming gases and a large disparity of response and recovery time constants which often leads to an integrator-type of gas response. We show that this kind of sensor performance is related to the trend of semiconductor gas sensors to adsorb water vapor in multi-layer form and that this ability is sensitively influenced by the surface morphology. In particular we show that surface roughness in the nanometer range enhances desorption of water from multi-layer adsorbates, enabling them to respond more swiftly to changes in the ambient humidity. Further experiments reveal that reactive gases, such as NO2 and NH3, which are easily absorbed in the water adsorbate layers, are more easily exchanged across the liquid/air interface when the humidity in the ambient air is high.

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Section: Introductionmentioning

confidence: 99%

Effect of Water Vapor and Surface Morphology on the Low Temperature Response of Metal Oxide Semiconductor Gas Sensors

et al. 2015

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“…This solution formed a contact to an electrolyte-gated HEMT transistor (figure 1). HEMTs with recessed, non-metallized gates were used to increase their sensitivity [7]. The well-known, ultralow-noise level in combination with high-ohmic gate inputs of the 2dimensional electron gas devices enable the detection of tiny skin potential fluctuations.…”

Section: Sensors and Measurementsmentioning

confidence: 99%

Decomposition and modeling of signal shapes of single point cardiac monitoring

Hesar

Munief

Müller

et al. 2020

Current Directions in Biomedical Engineering

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We introduce a novel method for electronic recording of cardiac signals from a single point at the skin in contrast to classical differential electrocardiography (ECG). Ultralownoise transistor devices with an adaptable, auto-stabilizing transimpedance amplifier are able to measure tiny skin potential modulations from a single contact electrode located at an individual’s wrist (single-point cardiography-SPC). Although SPC signals were highly prone to interspersed noise, they contained periodic patterns. In an electromagnetically shielded setting, we could clearly extract breathing and cardiac rhythms from the acquired SPC signals. As the reference, we measured ECG in parallel. Several signal-processing techniques like smoothening, correlation, decomposition and signal extraction showed that SPC signals contain breathing and periodic heart potential variations, which are time-correlated with ECG. In the future, we intent to use this novel technique to measure heart signals from patients in different health conditions.

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“…Such sensitivity would clearly outperform the sensitivity of existing IMS instruments. Other attempts at attaining high sensitivity involve nanostructures formed from mono-crystalline semiconductor materials with surfaces that had been modified to induce gas sensitivity [ 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 ]. In such nanostructures, gas sensitivity is induced by surface oxidation and/or by surface functionalization with specifically chosen organic ligands.…”

Section: Achievements Future Challenges and Outlookmentioning

confidence: 99%

Solid-State Gas Sensors: Sensor System Challenges in the Civil Security Domain

et al. 2016

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The detection of military high explosives and illicit drugs presents problems of paramount importance in the fields of counter terrorism and criminal investigation. Effectively dealing with such threats requires hand-portable, mobile and affordable instruments. The paper shows that solid-state gas sensors can contribute to the development of such instruments provided the sensors are incorporated into integrated sensor systems, which acquire the target substances in the form of particle residue from suspect objects and which process the collected residue through a sequence of particle sampling, solid-vapor conversion, vapor detection and signal treatment steps. Considering sensor systems with metal oxide gas sensors at the backend, it is demonstrated that significant gains in sensitivity, selectivity and speed of response can be attained when the threat substances are sampled in particle as opposed to vapor form.

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Enhanced detection of NO2 with recessed AlGaN/GaN open gate structures

Cited by 21 publications

References 32 publications

Effect of Water Vapor and Surface Morphology on the Low Temperature Response of Metal Oxide Semiconductor Gas Sensors

Effect of Water Vapor and Surface Morphology on the Low Temperature Response of Metal Oxide Semiconductor Gas Sensors

Decomposition and modeling of signal shapes of single point cardiac monitoring

Solid-State Gas Sensors: Sensor System Challenges in the Civil Security Domain

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