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Recent developments in the domain of electronic materials and devices have attracted the interest of researchers toward flexible and printable electronic components like organic transistors, printable electrodes and sensors. Zinc Oxide (ZnO) nanowires (NWs) possess a number of excellent properties like high mobility, large exciton binding energy and the direct-band gap in addition to large piezoelectric coefficients. Here, we report on flexible piezo-resistive sensor based on Indium tin oxide (ITO)-coated Polyethylene tetrathalate (PET) substrate. The device shows sensitivity in terms of change in resistance from 100 {\Omega} to 2.4 K{\Omega} at an applied potential of 5V upon bending from flat to 95 degrees. The 1-D nanowire flexible device in its flat state shows saturated output current. We observed ten folds enhanced variation as compared to previous reports. Improved sensitivity was observed in our experiments due to fewer defects in CVD-grown NWs as compared to others where hydrothermally grown nanowires were used. The methodology of device fabrication reported here requires less time and enables efficient devices for the realization of flexible and wearable technology., Comment: 24 pages, 5 figures

Future generation technologies demand high efficiency photodetectors to enable sensing and switching devices for ultrafast communication and machine vision. This require direct-band gap materials with high photosensitivity, high detectivity and high quantum efficiency. Monolayered two- Dimensional (2D)-Semiconductors based photodetectors are the most promising materials for such applications, although experimental realization has been limited due to unavailability of high quality sample. In the current manuscript, we report about WS$_2$ based photodetector having sensitivity of 290 AW-1 upon 405 nm excitation and incident power density as low as 0.06 mW/cm$^2$. The fabricated device shows detectivity of 52*10^14 with external quantum efficiency of 89*10$^3$%. The observed superior photo-response parameters of CVD grown WS$_2$ based photodetector as compared to Si-detectors establishes it capability to replace the Si-photodetectors with monolayered ultrathin device having superior performance parameters., Comment: 26 Pages, 8 figures

The growth of large crystallite continuous monolayer materials like molybdenum disulfide (MoS$_2$) with desired morphology via chemical vapor deposition (CVD) remains a challenge. In CVD, the complex interplay of various factors like growth temperature, precursors, and nature of the substrate decides the crystallinity, crystallite size, and coverage area of the grown MoS$_2$ monolayer. In the present work, we report about the role of weight fraction of molybdenum trioxide (MoO$_3$), Sulfur, and carrier gas flow rate towards nucleation and monolayer growth. The concentration of MoO$_3$ weight fraction has been found to govern the self-seeding process and decides the density of nucleation sites affecting morphology and coverage area. Carrier gas flow of 100 sccm argon results into large crystallite continuous films with lower coverage area (70 %), while the flow rate of 150 sccm results into 92 % coverage area with reduced crystallite size. Through systematic variation of experimental parameters, we have established the recipe for the growth of large crystallite atomically thin MoS$_2$ suitable for optoelectronic devices., Comment: 31 pages, 10 figures

Carbon Quantum dots (CQD's) are nanoscale sp2 hybridized carbon particles. In this work, we present a simple one-step synthesis of CQDs from the electrochemical shredding method and technique to control its size during its growth process. A graphite rod extracted from commercially available pencil batteries was used as electrode: source of carbon. CQDs of varying sizes were synthesized through controlled current to the solution for etching and Sodium dodecyl sulfate (SDS) as capping agent during growth. CQD's of controlled sizes as formed can be used as fluorescent marker for bio-imaging and sensing platform for wide range of applications., Comment: 21 Pages, 7 figures

Electrical measurement of nano-scale devices and structures requires skills and hardware to make nano-contacts. Such measurements have been difficult for number of laboratories due to cost of probe station and nano-probes. In the present work, we have demonstrated possibility of assembling low cost probe station using USB microscope (US $ 30) coupled with in-house developed probe station. We have explored the effect of shape of etching electrodes on the geometry of the microprobes developed. The variation in the geometry of copper wire electrode is observed to affect the probe length (0.58 mm to 2.15 mm) and its half cone angle (1.4 to 8.8 degree). These developed probes were used to make contact on micro patterned metal films and was used for electrical measurement along with semiconductor parameter analyzer. These probes show low contact resistance ( 4 ohm) and follows ohmic behavior. Such probes can be used for laboratories involved in teaching and multidisciplinary research activities and Atomic Force Microscopy., Comment: 21 pages, 4 figures