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

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2551 ◽  
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.

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

2012 ◽  
Vol 717-720 ◽  
pp. 1195-1198
Author(s):  
Geunsik Lim ◽  
Tariq Manzur ◽  
Aravinda Kar
Keyword(s):  
Valence Band ◽  
Energy Gap ◽  
Gas Sensing ◽  
Optical Signal ◽  
Acceptor Level ◽  
Spectral Bands ◽  
Sensing Applications ◽  
Electro Optic ◽  
Midwave Infrared ◽  
P Type

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.

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

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1116 ◽  
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.

CNTFET Gas Sensors Using SWCNT Mats: Method for Low-cost Fabrication, Solution to Improve Selectivity, Experimental Results using Interfering Agents

2009 ◽  
Vol 1204 ◽  
Author(s):  
Paolo Bondavalli ◽  
Louis Gorintin ◽  
Pierre Legagneux ◽  
Didier Pribat ◽  
Laurent Caillier ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Gas Sensors ◽  
Field Effect ◽  
Gas Sensing ◽  
Field Effect Transistors ◽  
Low Cost ◽  
Experimental Results ◽  
Flexible Substrates ◽  
Metal Electrodes ◽  
Sensing Applications

AbstractThe first paper showing the great potentiality of Carbon Nanotubes Field Effect transistors (CNTFETs) for gas sensing applications was published in 2000 [1]. It has been demonstrated that the performances of this kind of sensors are extremely interesting: a sensitivity of around 100ppt (e.g. for NO2 [2]) has been achieved in 2003 and several techniques to improve selectivity have been tested with very promising results [2]. The main issues that have not allowed, up to now, these devices to strike more largely the market of sensors, have been the lack of an industrial method to obtain low-cost devices, a demonstration of their selectivity in relevant environments and finally a deeper study on the effect of humidity and the possible solutions to reduce it. This contribution deals with CNTFETs based sensors fabricated using air-brush technique deposition on large surfaces. Compared to our last contribution [3], we have optimized the air-brush technique in order to obtain high performances transistors (Log(Ion)/Log(Ioff) ∼ 5/6) with highly reproducible characteristics : this is a key point for the industrial exploitation. We have developed a machine which allows us the dynamic deposition on heated substrates of the SWCNT solutions, improving dramatically the uniformity of the SWCNT mats. We have performed tests using different solvents that could be adapted as a function of the substrates (e.g. flexible substrates). Moreover these transistors have been achieved using different metal electrodes (patented approach [4]) in order to improve selectivity. Results of tests using NO2, NH3 with concentrations between ∼ 1ppm and 10ppm will be shown during the meeting.

scholarly journals Microstrip Array Ring FETs with 2D p-Ga2O3 Channels Grown by MOCVD

Photonics ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 578
Author(s):  
Manijeh Razeghi ◽  
Junhee Lee ◽  
Lakshay Gautam ◽  
Jean-Pierre Leburton ◽  
Ferechteh H. Teherani ◽  
...  
Keyword(s):  
Field Effect Transistors ◽  
Chemical Vapor ◽  
Drain Current ◽  
Significant Advance ◽  
Growth Time ◽  
Organic Chemical ◽  
Transmission Electron ◽  
Metal Organic ◽  
P Type ◽  
Type Conduction

Gallium oxide (Ga2O3) thin films of various thicknesses were grown on sapphire (0001) substrates by metal organic chemical vapor deposition (MOCVD) using trimethylgallium (TMGa), high purity deionized water, and silane (SiH4) as gallium, oxygen, and silicon precursors, respectively. N2 was used as carrier gas. Hall measurements revealed that films grown with a lower VI/III ratio had a dominant p-type conduction with room temperature mobilities up to 7 cm2/Vs and carrier concentrations up to ~1020 cm−3 for thinner layers. High resolution transmission electron microscopy suggested that the layers were mainly κ phase. Microstrip field-effect transistors (FETs) were fabricated using 2D p-type Ga2O3:Si, channels. They achieved a maximum drain current of 2.19 mA and an on/off ratio as high as ~108. A phenomenological model for the p-type conduction was also presented. As the first demonstration of a p-type Ga2O3, this work represents a significant advance which is state of the art, which would allow the fabrication of p-n junction based devices which could be smaller/thinner and bring both cost (more devices/wafer and less growth time) and operating speed (due to miniaturization) advantages. Moreover, the first scaling down to 2D device channels opens the prospect of faster devices and improved heat evacuation.

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

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

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

2015 ◽  
Vol 209 ◽  
pp. 287-296 ◽  
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

scholarly journals Morphology and electrical characteristics of p-type ZnO microwires with zigzag rough surfaces induced by Sb doping

RSC Advances ◽  
2018 ◽  
Vol 8 (61) ◽  
pp. 35023-35030 ◽  
Author(s):  
Linlin Shi ◽  
Luchao Du ◽  
Yingtian Xu ◽  
Liang Jin ◽  
He Zhang ◽  
...  
Keyword(s):  
Rough Surface ◽  
Doping Concentration ◽  
Rough Surfaces ◽  
Electrical Characteristics ◽  
Sb Doping ◽  
P Type ◽  
Type Conduction

Sb-doped microwires which have a zigzag rough surface demonstrate p-type conduction and enhanced rectifying behavior with increasing Sb doping concentration.

Large-scale Production of Selective Gas Sensors Based on Carbon Nanotube Mats Transistors

2010 ◽  
Vol 1253 ◽  
Author(s):  
Louis Gorintin ◽  
Paolo Bondavalli ◽  
pierre legagneux ◽  
Marc Chatelet
Keyword(s):  
Gas Sensors ◽  
Large Scale ◽  
Gas Sensing ◽  
Field Effect Transistors ◽  
Low Cost ◽  
Flexible Substrates ◽  
Scale Production ◽  
Metal Electrodes ◽  
Sensing Applications ◽  
Large Scale Production

AbstractThe first paper showing the great potentiality of Carbon Nanotubes Field Effect transistors (CNTFETs) for gas sensing applications was published in 2000 [1]. It has been demonstrated that the performances of this kind of sensors are extremely interesting : a sensitivity of around 100ppt (e.g. for NO2 [2]) has been achieved in 2003 and several techniques to improve selectivity have been tested with very promising results [2]. The main issues that have not allowed, up to now, these devices to strike more largely the market of sensors, have been the lack of an industrial method to obtain low-cost devices, a demonstration of their selectivity in relevant environments and finally a deeper study on the effect of humidity and the possible solutions to reduce it. This contribution deals with CNTFETs based sensors fabricated using air-brush technique deposition on large surfaces. Compared to our last contribution [3], we have optimized the air-brush technique in order to obtain high performances transistors (Log(Ion)/ Log(Ioff) ~ 5/6) with highly reproducible characteristics : this is a key point for the industrial exploitation. We have developed a machine which allows us the dynamic deposition on heated substrates of the SWCNT solutions, improving dramatically the uniformity of the SWCNT mats. We have performed tests using different solvents that could be adapted as a function of the substrates (e.g. flexible substrates). Moreover these transistors have been achieved using different metal electrodes (patented approach [4]) in order to improve selectivity. Results of tests using NO2, NH3 with concentrations between ~ 1ppm and 10ppm will be shown during the meeting.

Effects of the Surface Condition of the Substrates on the Electrical Characteristics of 4H-SiC MOSFETs

2009 ◽  
Vol 615-617 ◽  
pp. 781-784 ◽  
Author(s):  
Takeshi Ohshima ◽  
Shinobu Onoda ◽  
Toshiro Kamada ◽  
Kazutoshi Hotta ◽  
Kenji Kawata ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Field Effect Transistors ◽  
Surface Condition ◽  
Drain Current ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Electrical Characteristics ◽  
Surface Conditions ◽  
P Type

Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) were fabricated on p-type epitaxial 4H-SiC substrates with different surface conditions and these electrical characteristics were compared. The MOSFETs on Chemical Mechanical Polished substrates showed the drain current of the order of 10-12A at a gate voltage of 0 V, and the value of the drain current increased with increasing the surface roughness of substrates. With decreasing the surface roughness of substrates, the values of the threshold voltage decreased and the quality of gate oxide became better.

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