Gas Sensing with Atomic Layer Deposited Dielectric Thin Film

2014 ◽  
Vol 605 ◽  
pp. 71-74 ◽  
Author(s):  
V.A.T. Dam ◽  
M.A. Blauw ◽  
S.H. Brongersma ◽  
R. van Schaijk
Keyword(s):  
Thin Film ◽  
Ambient Temperature ◽  
Deposition Temperature ◽  
Gas Sensing ◽  
Atomic Layer ◽  
Sensitive Material ◽  
Metal Insulator ◽  
Dielectric Thin Film ◽  
Post Annealing ◽  
Mis Capacitor

A metal-insulator-semiconductor (MIS) capacitor with La2O3 dielectric is proposedin this work as a sensor for measuring CO2 in air. In this device, a 10 nm thick La2O3 dielectriclayer, which serves as a CO2 sensitive material, was atomic-layer-deposited (ALD) on p-typesilicon. Change in the at band voltage (VFB) of the MIS capacitor due to the reactionbetween CO2 and oxide layer and its interfaces, is used as the gas sensitive parameter of thesensor. The deposition temperature for the La2O3 layer has been optimized for maximizingCO2 sensitivity. The process ow including post annealing (rapid thermal annealing) has beenoptimized to allow further possibility to integrate the sensor with CMOS read-out circuitries. The sensor shows a sensitivity of 84 mV per decade to CO2 in air in a concentration rangefrom 300-5000 ppm at ambient temperature with a response time (t90) of 34 minutes.

Mobility Enhancement and OFF Current Suppression in Atomic-Layer-Deposited ZnO Thin-Film Transistors by Post Annealing in O2

2014 ◽  
Vol 35 (12) ◽  
pp. 1266-1268 ◽  
Author(s):  
Yang Geng ◽  
Wen Yang ◽  
Hong-Liang Lu ◽  
Yuan Zhang ◽  
Qing-Qing Sun ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Atomic Layer ◽  
Zno Thin Film ◽  
Post Annealing

IMPROVING RESERVOIR TESTING AND SAMPLING IN H2S CONTAMINATED FLUIDS BY ADAPTING STATE-OF-THE-ART SEMICONDUCTOR THIN FILM TECHNOLOGY FOR DOWNHOLE TESTER TOOLS

2021 ◽  
Author(s):  
Jimmy Price ◽  
◽  
Darren Gascooke ◽  
Anthony Van Zuilekom ◽  
Christopher Jones ◽  
...  
Keyword(s):  
Thin Film ◽  
State Of The Art ◽  
Drilling Fluid ◽  
Semiconductor Industry ◽  
Atomic Layer ◽  
Prototype System ◽  
Dielectric Thin Film ◽  
Fluid Identification ◽  
Conformal Coverage ◽  
Downhole Tool

Accurate reservoir fluid identification and sampling of hydrogen sulfide (H2S) contaminated fluids is difficult to achieve due its consumption by the interior of downhole tool surfaces prior to sampling or measurement. For low PPM level concentrations, this fact does not change, despite recent tool advances utilizing NACE compliant materials. Consequently, H2S concentrations are typically under-reported which adversely affects production and presents significant health safety and environment concerns. Historically, only sampling bottles have been coated to preserve H2S concentrations during transit to laboratories with a material that is resistant to H2S reactivity to enable more representative measurements. However, only very recent efforts have transitioned the focus toward successfully coating the interior of the tools. This paper details a state-of-the-art technology, initially developed and heavily leveraged from the semiconductor industry. The technology is adapted to coat the interior surfaces of downhole tools with a chemically resistant dielectric thin film. New developments now provide the benefit of the process being safe, able to be performed at atmospheric pressure and temperature conditions, and portable; thus, allowing the coating process to be deployed to field locations. The method involves atomic layer deposition (ALD) technology to be plumbed in directly to a downhole tool and conformally deposit a thin layer (e.g. < 1 micron) of highly durable H2S-resistant sapphire to the entire interior tool surface. An automated procedure has been developed allowing the versatility to accommodate a number of unique geometries inherent of different formation tester configurations. New advances in Quartz Crystal Microbalance sensors are also realized in-situ to optimize (in real-time) the efficiency of the process and ensure uniform and conformal coverage is obtained in the fastest and safest manner. Laboratory testing on a prototype system demonstrated uniform and conformal coverage of a ~ 500 nm thick sapphire film resistant to flaking and scratching. Accelerated lifetime stress testing demonstrated high durability relative to expected tool life. Testing of coated and uncoated tools show the coating is successful at the 50ppm level H2S for up to 4 days. These results are contrasted with similar tool body samples not coated with the H2S-resistant ALD sapphire and subject to the same H2S conditions. To show the coating’s durability, subsequent experiments flowed mud-based drilling fluid through both the tool body and sample chambers, followed by thorough cleaning and successful repeating the same 50ppm H2S test. Exposure of the sapphire coated tool body and sample chambers to various concentrations of H2S demonstrated zero loss. Ultimately this technique represents a new opportunity to gather representative formation samples containing low concentrations of H2S.

Application of Modified PANI-ZnO Composites for NH3Gas Sensor at Ambient Temperature

2020 ◽  
Vol 42 (3) ◽  
pp. 390-390
Author(s):  
Naimat Ullah Naimat Ullah ◽  
Anwar Ul Haq Ali Shah Anwar Ul Haq Ali Shah ◽  
Fazal Akbar Jan Fazal Akbar Jan ◽  
Rotaba Ansir Rotaba Ansir ◽  
Wali Muhammad Wali Muhammad
Keyword(s):  
Thin Film ◽  
Zinc Oxide ◽  
Ambient Temperature ◽  
Zinc Oxide Nanoparticles ◽  
Gas Sensing ◽  
Visible Spectrum ◽  
Xrd Analysis ◽  
Oxide Nanoparticles ◽  
Ammonia Gas ◽  
Uv Visible

Polyaniline and zinc oxide nanoparticles were successfully synthesized through inverse emulsion polymerization method and hydrothermal method respectively. For ammonia gas sensing using LCR meter thin film of the composite was fabricated by using spin coater. The functional groups, morphological, optical, structural properties of zinc oxide nanoparticles, polyaniline (emeraldine salt) and composites were investigated by FTIR spectroscopy, Scanning electron microscopy (SEM), UV- Visible spectroscopy and XRD analysis. The formation of ZnO particles of different shapes in the nano range was confirmed from UV-visible and XRD analysis. UV visible spectrum shows the formation of nanoparticles of ZnO. Thin film of Polyaniline/zinc oxide composites were deposited on the surface of copper interdigitated electrode. The fabricated device showed sensitivity to ammonia gas (NH3) at ambient temperature (300 K). It was observed that the resistance is decreases with the increase of volume of ammonia gas. The electrical properties were also investigated of the different concentration of nanocomposite. Optimum sensing response was achieved with PANI in the presence of 50 wt% ZnO nanoparticles. It may also be inferred from this study that the solution mixing process to produce composites has promising future if handled carefully.

Au/Pd Bimetallic Nanoparticles Decorated SnSe2 Thin Films for NO2 Detection

2021 ◽  
Vol 21 (9) ◽  
pp. 4916-4920
Author(s):  
Sanju Rani ◽  
Manoj Kumar ◽  
Yogesh Singh ◽  
Vidya Nand Singh
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Ambient Temperature ◽  
Surface Area ◽  
Gas Sensing ◽  
Sensing Properties ◽  
Toxic Gases ◽  
Gas Sensing Properties ◽  
Recovery Times ◽  
Response And Recovery

In order to have a check and balance of the toxic gases in the environment, various kinds of sensors are currently being researched upon. As many of the toxic gases are also inflammable, therefore, there is a constant search for materials which can detect the gases at lower temperatures. Also, it is important that the sensor is selective for a particular gas. To meet such requirements, nanos-tructured materials are extensively being explored for such gas sensing applications, due to their large effective surface area. And, in order to further improve the gas sensing properties, metal catalysts are deposited over such nanomaterials. The smaller sized nanoparticles show better catalytic activity due to its effective larger surface area per unit volume. Depositing bimetallic materials is thus advantageous, since it can reduce the size of nanoparticles produced. In this work, ~7 nm thick Au/Pd thin film was sputter-coated over SnSe2 nanostructured thin films. SnSe2 thin film were deposited by thermally evaporating SnSe2 powder. The materials were characterized for their structural, morphological and gas sensing properties. The ambient temperature response for 5 parts per million (ppm) NO2 gas was measured to be 117%, with the response and recovery times being 10 and 19 seconds, respectively. The performance of the sensor improved with increase in the gas concentration and for 10 ppm gas, the recorded response was 137%, with the corresponding response and recovery times being 9 and 8 seconds, respectively. The limit of detection was 655 parts per billion (ppb). The mechanism of ambient temperature high response and low response/recovery times have been discussed based on physisorption, charge transfer, Au/Pd decoration and SnSe–SnSe2 based p–n junction. In addition, an important aspect of this work worth pointing out is the deposition of a thin film consisting of nanostructured network using an industrially viable thermal evaporation method. Thus, this work opens a new dimension for 2D materials that can be used for selective gas detection at ambient temperature.

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