@article { ISI:000370211400055, title = {Highly transparent wafer-scale synthesis of crystalline WS2 nanoparticle thin film for photodetector and humidity-sensing applications}, journal = {ACS Applied Materials \& Interfaces}, volume = {8}, number = {5}, year = {2016}, month = {FEB}, pages = {3359-3365}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

In the present investigation, we report a one-step synthesis method of wafer-scale highly crystalline tungsten disulfide (WS2) nanoparticle thin film by using a modified hot wire chemical vapor deposition (HW-CVD) technique. The average size of WS2 nanoparticle is found to be 25-40 nm over an entire 4 in. wafer of quartz substrate. The low-angle XRD data of WS2 nanoparticle shows the highly crystalline nature of sample along with orientation (002) direction. Furthermore, Raman spectroscopy shows two prominent phonon vibration modes of E12g and A1g at similar to 356 and similar to 420 cm(-1), respectively, indicating high purity of material. The TEM analysis shows good crystalline quality of sample. The synthesized WS2 nanoparticle thin film based device shows good response to humidity and good photosensitivity along with good long-term stability of the device. It was found that the resistance of the films decreases with increasing relative humidity (RH). The maximum humidity sensitivity of 469\% along with response time of similar to 12 s and recovery time of similar to 13 s were observed for the WS2 thin film humidity sensor device. In the case of photodetection, the response time of similar to 51 s and recovery time of similar to 88 s were observed with sensitivity similar to 137\% under white light illumination. Our results open up several avenues to grow other transition metal dichalcogenide nanoparticle thin film for large-area nanoelectronics as well as industrial applications.

}, keywords = {chemical vapor deposition, humidity sensor, nanoparticle, photosensor, thin film, tungsten disulfide}, issn = {1944-8244}, doi = {10.1021/acsami.5b11325}, author = {Pawbake, Amit S. and Waykar, Ravindra G. and Late, Dattatray J. and Jadkar, Sandesh R.} } @article { ISI:000375521000042, title = {Humidity sensing and photodetection behavior of electrochemically exfoliated atomically thin-layered black phosphorus nanosheets}, journal = {ACS Applied Materials \& Interfaces}, volume = {8}, number = {18}, year = {2016}, month = {MAY}, pages = {11548-11556}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Recent investigations on two-dimensional black phosphorus material mainly highlight work on few atomic layers and multilayers. It is still unknown if the black phosphorus atomically thin sheet is an ideal structure for the enhanced gas solid interactions due to its large surface area. To further investigate this concern, we have synthesized few atomic layer thick nanosheets of black phosphorus using an electrochemical exfoliation method. The surface morphology and thickness of the nanosheet were identified using AFM, TEM, and Raman spectroscopy. The black phosphorus nanosheet thick film device was used for the gas sensing application with exposure to different humidites. Further, the few layer black phosphorus nanosheet based transistor shows good mobility and on/off ratio. The UV light irradiation on the black phosphorus nanosheet shows good response time. The overall results show that the few layer thick film of black phosphorus nanosheets sample exhibits creditable sensitivity and better recovery time to be used in humidity sensor and photodetector applications.

}, keywords = {black phosphorus, electrochemical exfoliation, humidity sensor, photodetector}, issn = {1944-8244}, doi = {10.1021/acsami.5b10247}, author = {Erande, Manisha B. and Pawar, Mahendra S. and Late, Dattatray J.} } @article {46044, title = {Superior humidity sensor and photodetector of mesoporous ZnO nanosheets at room temperature}, journal = {Sensors and Actuators B-Chemical}, volume = {293}, year = {2019}, month = {AUG}, pages = {83-92}, type = {Article}, abstract = {

Miniaturized sensor technology is vastly demanding multifunctional materials to fulfill many requirements simultaneously; instead of integrating various sensors into a single device. Efficient operation of these miniaturized sensors at room temperature is highly feasible and cost-effective. The humidity sensing and photodetection is precise merit of sensing in special usage like artificial skin. Sensitivity enhancement in both humidity and photodetection required the high surface area for adsorption as well as a high charge transfer mechanism. The two dimensional (2D) zinc oxide nanosheets (ZnO NS) is the ultimate structure for dimensionally confined transport properties owing to the specific surface atomic configuration that results in high sensitivity, low operating temperature, fast response and recovery, and improved selectivity. Furthermore, introducing porosity into 2D nanostructures has opened new opportunities to enhance the efficiency of sensors and detectors via increasing large surface area and tunable physical and chemical properties. Here we report preparation of mesoporous and highly crystalline 2D ZnO NS by a single step, template free, cost-effective chemical method. The structural and morphological characterizations of ZnO NS are carried out using XRD, FESEM, XPS, TEM respectively. The high-resolution TEM images emphasize sheet-like morphology with a thickness of around 18-22 nm. Further the mesoporous ZnO NS (MZNS) with the pore size between 5-10 nm are achieved by simple heat-treatment. XPS and PL study is confirming the oxygen deficiency in MZNS. The MZNS exhibits an excellent responsivity than PZNS with a fast response and rapid recovery time of 25 s and 5 s respectively along with good cyclic stability which is highly crucial for smart humidity sensor. Furthermore, it considerably enhances photo-sensor performance than pristine ZnO NS (PZNS) with (similar to)1 s response time as well as (similar to)1 s recovery time along with better stability. These promising results illustrate the great potential of MZNS for next-generation humidity sensors and photodetectors.

}, keywords = {humidity sensor, Mesoporous, nanosheets, Photo-detector}, issn = {0925-4005}, doi = {10.1016/j.snb.2019.04.086}, author = {Gupta, Shobhnath P. and Pawbake, Amit S. and Sathe, Bhaskar R. and Late, Dattatray J. and Walke, Pravin S.} }