Laser-Doped SiC as Wireless Remote Gas Sensor Based on Semiconductor Optics

An uncooled SiC-based electro-optic device is developed for gas sensing applications. P-type dopants Ga, Sc, P and Al are incorporated into an n-type crystalline 6H-SiC substrate by a laser doping technique for sensing CO2, CO, NO2 and NO gases, respectively. Each dopant creates an acceptor energy level within the bandgap of the substrate so that the energy gap between this acceptor level and the valence band matches the quantum of energy emitted by the gas of interest. The photons of the gas excite electrons from the valence band to the acceptor level, which alters the electron density in these two states. Consequently, the refractive index of the substrate changes, which, in turn, modifies the reflectivity of the substrate. This change in reflectivity represents the optical signal of the sensor, which is probed remotely with a laser such as a helium-neon laser. Although the midwave infrared (3-5 mm) band is studied in this paper, the approach is applicable to other spectral bands.

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A Room Temperature Gas Sensor Based on Sulfonated SWCNTs for the Detection of NO and NO2

Sensors ◽

10.3390/s19051116 ◽

2019 ◽

Vol 19 (5) ◽

pp. 1116 ◽

Cited By ~ 6

Author(s):

Eusebiu Ionete ◽

Stefan Spiridon ◽

Bogdan Monea ◽

Elena Stratulat

Keyword(s):

Room Temperature ◽

Gas Sensing ◽

Electrical Response ◽

Long Term Stability ◽

Sensing Applications ◽

Specific Configuration ◽

P Type ◽

Walled Carbon Nanotubes ◽

Type Response

The electrical response of sulfonated single-walled carbon nanotubes (SWCNTs) to NO and NO2, for gas sensing applications, at room temperature, is reported in this work. A specific configuration based on SWCNT deposition between double pair configuration gold electrodes, supported on a substrate, was considered for the sensing device; employed characterization technique where FTIR and SEM. The experimental results showed a p-type response of the sulfonated SWCNTs, with decrease in resistance, under exposure to NO gas (40–200 ppb) and NO2 (40–200 ppb). Also, the sensor responses to successive exposures at NO2 800 ppb together with investigation of long term stability, at 485 ppb for NO, are reported. The reaction mechanism in case of NO and NO2 detection with sulfonated SWCNTs is presented.

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Tuning the Polarity of MoTe2 FETs by Varying the Channel Thickness for Gas-Sensing Applications

Sensors ◽

10.3390/s19112551 ◽

2019 ◽

Vol 19 (11) ◽

pp. 2551 ◽

Cited By ~ 9

Author(s):

Asha Rani ◽

Kyle DiCamillo ◽

Md Ashfaque Hossain Khan ◽

Makarand Paranjape ◽

Mona E. Zaghloul

Keyword(s):

Schottky Barrier Height ◽

Gas Sensing ◽

Field Effect Transistors ◽

Thickness Variation ◽

Electrical Characteristics ◽

Conductivity Type ◽

Sensing Applications ◽

Channel Thickness ◽

P Type ◽

Type Conduction

In this study, electrical characteristics of MoTe2 field-effect transistors (FETs) are investigated as a function of channel thickness. The conductivity type in FETs, fabricated from exfoliated MoTe2 crystals, switched from p-type to ambipolar to n-type conduction with increasing MoTe2 channel thickness from 10.6 nm to 56.7 nm. This change in flake-thickness-dependent conducting behavior of MoTe2 FETs can be attributed to modulation of the Schottky barrier height and related bandgap alignment. Change in polarity as a function of channel thickness variation is also used for ammonia (NH3) sensing, which confirms the p- and n-type behavior of MoTe2 devices.

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Band gap tuning of p-type al-doped tio2 thin films for gas sensing applications

Thin Solid Films ◽

10.1016/j.tsf.2020.138382 ◽

2020 ◽

Vol 714 ◽

pp. 138382

Author(s):

Mohammad Nurul Islam ◽

Jiban Podder ◽

Khandker Saadat Hossain ◽

Suresh Sagadevan

Keyword(s):

Thin Films ◽

Band Gap ◽

Gas Sensing ◽

Tio2 Thin Films ◽

Doped Tio2 ◽

Sensing Applications ◽

P Type ◽

Band Gap Tuning

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p-Type copper aluminum oxide thin films for gas-sensing applications

Sensors and Actuators B Chemical ◽

10.1016/j.snb.2014.11.116 ◽

2015 ◽

Vol 209 ◽

pp. 287-296 ◽

Cited By ~ 25

Author(s):

C. Baratto ◽

R. Kumar ◽

G. Faglia ◽

K. Vojisavljević ◽

B. Malič

Keyword(s):

Thin Films ◽

Aluminum Oxide ◽

Gas Sensing ◽

Oxide Thin Films ◽

Sensing Applications ◽

Copper Aluminum Oxide ◽

Copper Aluminum ◽

P Type

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The Effect of CH4 and CO2 Exposure on Carbon Nanotubes Electrical Resistance

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.214.655 ◽

2011 ◽

Vol 214 ◽

pp. 655-661 ◽

Cited By ~ 1

Author(s):

Amin Firouzi ◽

Shafreeza Sobri ◽

Faizah Mohd Yasin ◽

Fakhru'l Razi Ahmadun

Keyword(s):

Carbon Nanotubes ◽

Electrical Resistance ◽

Gas Sensing ◽

Quartz Substrate ◽

Chemical Vapor ◽

High Sensitivity ◽

Sensing Applications ◽

Type Semiconductor ◽

Adsorption Of Co2 ◽

P Type

This research was carried out to monitor and investigate the gas sensing effects on carbon nanotubes (CNTs) by a systematic study of the variations in the electrical resistance as sensor signal induced by adsorption of CO2 and CH4 gaseous molecules. The CNTs were synthesized by Floating Catalyst Chemical Vapor Deposition (FC-CVD) method on quartz substrate under benzene bubble at temperature of 700°C. Then, they were tested for gas sensing applications operating at room temperature. Upon exposure to gaseous molecules, the electrical resistance of CNTs dramatically increased for both CO2 and CH4 gases with short response time and high sensitivity. It was also observed that the CNTs device behaves as a p-type semiconductor when exposed to gaseous molecules. In addition, the recovery of the sensors and mechanism of gas sensing procedure are discussed.

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Synthesis of Cu2O-Modified Reduced Graphene Oxide for NO2 Sensors

Sensors ◽

10.3390/s21061958 ◽

2021 ◽

Vol 21 (6) ◽

pp. 1958

Author(s):

Manman Huang ◽

Yanyan Wang ◽

Shuyang Ying ◽

Zhekun Wu ◽

Weixiao Liu ◽

...

Keyword(s):

Graphene Oxide ◽

Reduced Graphene Oxide ◽

Gas Sensing ◽

Thermal Reduction ◽

Oxide Semiconductors ◽

Research Attention ◽

Sensing Applications ◽

Reduced Graphene ◽

Significant Research ◽

P Type

Nowadays, metal oxide semiconductors (MOS)-reduced graphene oxide (rGO) nanocomposites have attracted significant research attention for gas sensing applications. Herein, a novel composite material is synthesized by combining two p-type semiconductors, i.e., Cu2O and rGO, and a p-p-type gas sensor is assembled for NO2 detection. Briefly, polypyrrole-coated cuprous oxide nanowires (PPy/Cu2O) are prepared via hydrothermal method and combined with graphene oxide (GO). Then, the nanocomposite (rGO/PPy/Cu2O) is obtained by using high-temperature thermal reduction under Ar atmosphere. The results reveal that the as-prepared rGO/PPy/Cu2O nanocomposite exhibits a maximum NO2 response of 42.5% and is capable of detecting NO2 at a low concentration of 200 ppb. Overall, the as-prepared rGO/PPy/Cu2O nanocomposite demonstrates excellent sensitivity, reversibility, repeatability, and selectivity for NO2 sensing applications.

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