BITS Faculty Publications
Permanent URI for this communityhttp://localhost:4000/handle/123456789/1867
Browse
7 results
Search Results
Item Efficient acetone sensing by Pd nanoparticle loaded graphene Field Effect Transistor(IEEE, 2021) Hazra, ArnabIn this work we have reported Pd/GO FET nanocomposite field effect transistor (FET) based acetone sensor. Pd nanoparticle loaded graphene oxide (GO) was prepared by one step spray coating technique at room temperature. The morphological and structural characterizations of developed pure GO and Pd/GO samples were performed with field emission scanning electron microscopy (FESEM), Raman spectroscopy and UV-Vis spectroscopy techniques. The effect of gate voltage on sensors at different temperature range (25- 75°C) was investigated by I DS -V GS characteristic. GO and Pd/GO FET sensors showed optimum response at 50 °C temperature with and without applied gate voltage. The response of Pd/GO FET sensor was around 8 % under zero gate voltage (V GS = 0 V) at operating temperature of 50 °C. Due to the application of gate voltage near Dirac point voltage (V GS =V dirac ), both the sensors showed a significant increment in the response magnitude where pure GO exhibited 22 % and Pd/GO exhibited 45 % response in the exposure of 80 ppm acetone at 50°C. The Pd/GO FET sensor showed ~6 times amplification in sensitivity as the consequence of applied gate voltage.Item Bimetals (Au-Pd, Au-Pt) loaded WO3 hybridized graphene oxide FET sensors for selective detection of acetone(IEEE, 2022) Hazra, ArnabEfficient detection of acetone is important for a variety of applications in pharmaceutical, automotive industries, medical diagnosis etc. Surface modification is one of the potential method to enhance the sensitivity as well as selectivity of any sensors. In recent days, surface functionalization with bimetallic nanoparticles become attractive because of its enhanced catalytic properties and the possibility to form discrete heterojunctions. In this study, WO 3 flowered morphology was prepared by one step acid precipitation method and bimetallic nanoparticles of Au-Pd and Au-Pt were deposited on WO 3 /GO hybrid layer by one-step dip-coating process and fabricated a back gated field effect transistor (FET) structured sensor. Various morphological and structural characterizations were performed to study the various properties of the hybrid sensing layer. I D -V GS characteristics and the acetone sensing performance were measured for both the sensors i.e., Au-Pd/WO 3 /GO and Au-Pt/WO 3 /GO at room temperature. Among the two sensors, Au-Pt/WO 3 /GO FET sensor exhibited an appreciably high sensitivity of 56% towards 80 ppm acetone at room temperature under applied gate voltage (V GS ) of 1.2V. The lower detection limit of the Au-Pt/WO 3 /GO FET sensor was 400 ppb of acetone where it showed a 3 % response. The sensing mechanism envisages that the bimetallic loading in the ternary form of the nanocomposite enhanced sensitivity significantly by the spill-over effect. Also, the application of an optimized gate voltage amplified the sensitivity of the FET structured sensors.Item SrTiO3 passivated MXene (Ti3C2Tx) for efficient VOC detection in hazardous humid ambient(Elsevier, 2024-02) Hazra, ArnabHumidity interference is a crucial consideration in gas sensing technology for real-time applications. MXenes are new-age two-dimensional (2D) materials with unique properties making them promising candidates for gas sensors. However, the MXene surface with the hydrophilic functional groups (e.g., =O, –OH) is susceptible to water vapor. The passivation by a hydrophobic layer on MXene could be the best option to overcome humidity intrusion. We are introducing super hydrophobic SrTiO3 passivation on the MXene layer for humidity-tolerant volatile organic compound (VOC) sensing. Herein, 2D MXene (Ti3C2Tx) was physically oxidized at 350 °C for 24 h to create a TiO2 layer and subsequent coating of moisture-blocking SrTiO3 (STO) overlayer was achieved by hydrothermal route. Sensors were tested in different VOCs and showed the optimum results towards the acetone. The TiO2 formation in MXene enhanced the acetone sensing response (217%/50 ppm) compared to the pure Ti3C2TX MXene sensor (175%/50 ppm) in air at 150 °C. However, the MX and TiO2/MX sensors were lacking in the acetone sensing performance in a humid atmosphere (80% RH). STO/MX-12 h sensor showed outstanding moisture-resistant sensing behavior in humid atmospheres (0–80% RH). Apart from this, the STO/MX-12 h sensor showed a high response of 68% for 100 ppb of acetone with adequate repeatability, and excellent stability in 80%RH and 150 °C operating temperature. The hydrophilicity change in MXene after SrTiO3 passivation was optimized by contact angle study.Item Nanocrystalline p-TiO2 based MIS device for efficient acetone detection(IEEE, 2014) Hazra, ArnabPresent study investigated, the acetone sensing properties of Pd/TiO 2 /Si Metal Insulator Semiconductor (MIS) devices with nanocrystalline p-TiO 2 , with crystalline size ~8 nm as the sensing layer. p-TiO 2 thin film was synthesized using sol-gel method. After details structural characterization by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and electrical characterization by Van Der Pauw method, the MIS structure was fabricated employing drop coated p-Si substrate. Pd was deposited, on TiO 2 , as noble metal catalytic electrode while Al was taken as ohmic contact electrode from Si. The sensor study was carried out at relatively lower operating temperatures (50-200°C) for the acetone concentrations of 0.5-50ppm. It was found that MIS devices showed fast response/recovery with appreciable response magnitude in the entire temperature range for all the concentration. The faster response/recovery of MIS devices has been analyzed through an electrical equivalent model including the effect of barrier height between grain boundaries (GBs) and hole trapping at GBs interfaces.Item Low temperature acetone sensor based on Sol-gel grown nano TiO2 thin film(IEEE, 2013) Hazra, ArnabThin film Sol-gel grown nano TiO 2 based resistive sensor was developed to detect acetone at low temperature. Structural characterization were carried out using XRD, FESEM and AFM to ensure the crystalline, grain size and surface roughness of the TiO 2 thin film and anatase phase TiO 2 having particle size in order of 10 to 20 nm with average roughness 100nm. The thin film with catalytic Pd contact were investigated for acetone vapor sensing in the range of 150-250°C for acetone concentration 500-1500 ppm with N 2 as carrier gas. The maximum response 178 % approximately was obtained at the optimum temperature of 150 o C for 500 ppm acetone. The dynamic range of the sensor was also found to be quite appreciable (500-1500 ppm). The response and recovery time 42s and 44s respectively was recorded at 500 ppm at optimum temperature. The short term stability study indicated that the sensor is appreciably stable with a nominal baseline drift of ±6 %.Item Low temperature low ppm acetone detection by Pd/TiO2/p-Si Metal-Insulator-Semiconductor devices(IEEE, 2013-12) Hazra, ArnabIn this present investigation nanocrystalline TiO 2 based sensor was developed for low ppm level (10-100) acetone detection. TiO 2 thin film (Thickness: 1 μm) was prepared by solgel technique and deposited on the p-Si substrate (5 Ωcm, (100)) by dip coating method. Film was annealed at 450°C for 3 hours in air environment. XRD and FESEM study confirmed the (101) anatase growth with ~6-9 nm particle size. Pd electrode was deposited on the TiO 2 sensing layer to prepare the Pd/TiO 2 /p-Si Metal-Insulator-Semiconductor (MIS) device structure. A detailed acetone sensor study was performed for this MIS device in the temperature range of 100 to 200°C. Sensor showed a repeatable sensing performance with a appreciably fast response time of 7.7 s at 100°C towards 10 ppm acetone with corresponding recovery time of 13 s at 200°C in 10 ppm acetone. Response magnitude was increased from 3.2% to 6.4% with increasing the acetone concentration from 10 to 100 ppm at 200°C.Item Potentiality of Semiconducting Metal Oxide Nanoforms as Solid State Vapor Sensors(Springer, 2015) Hazra, ArnabNanostructured semiconducting metal oxides have been slotted as the potential material for its applications in gas/vapor sensing systems. During the last couple of decades, extensive efforts have been devoted in maximizing the parameters like sensitivity and selectivity and minimizing the response and recovery times. The efforts are essentially directed towards modification of chemical, dimensional and morphological attributes of the metal oxides. The evolution started with the optimization of particles size and thickness of the thin films, but was accelerated, particularly since last decade, with the incorporation of several unprecedented interesting nanoforms of metal oxides like nanorods, nanowires, nanosheets, nanohollowspheres and nanotubes. It has been established that the vapour/gas sensing characteristics (e.g., operating temperature, sensitivity, response time and recovery time) of the semiconducting oxides improved dramatically if the nanostructure is changed from three dimensional to two dimensional and then to one dimensional. Thus, the domain calls for basketting of the state of knowledge with the contemporary relevance. In view of the above, the present article aims to discuss the underlying mechanisms governing the formation of metal oxide nanoforms under different process routes and correlation of the structural attributes with the semiconducting behavior with special reference to the sensing of acetone vapor. The beginning of the chapter elaborates the necessity of nanoforms in improving the sensing performance with the help of grain surface/boundary model. Subsequently, different semiconducting oxide nanostructure/nanoform (like nanorods, nanowires, nanosheets, nanohollowspheres and nanotubes) synthesis and their sensing properties with emphasis on their respective advantages and bottlenecks have been discussed. The chapter concludes with the salient features of the advancement of oxide nanoform based acetone sensors and predicting the future direction of research.