arXiv subjects

Subhrajit Sikdar

Publications and source records attributed to Subhrajit Sikdar.

4 recordsLinked to original sources

arXiv2026

CVD grown bilayer MoS2 based artificial optoelectronic synapses for arithmetic computing and image recognition applications

Demand for lower computing power has rapidly increased. In this context, brain-inspired neuromorphic computing, which integrate data storage and processing, has attracted significant attention. Here, our study reveals that field effect transistors fabricated on chemical vapor deposited bilayer (2L) MoS2 films can mimic the functions of biological synapse. These devices demonstrate high level of pair pulse facilitation (PPF), short term to long term memory (STM-to-LTM) transition as well as learning-forgetting-relearning properties. Effect of light intensity, pulse number, pulse width and photon energy on the STM-to-LTM transition is studied. It has been found that the rate of depression of the memory state can be controlled using the gate bias. Electrical and optical energy consumptions per synaptic event are estimated to be as low as 280 fJ and 20 nJ, respectively. Furthermore, photocurrent in these devices is observed to increase linearly with the number of the excitation pulses. This property has been exploited to demonstrate different arithmetic operations by the device. Moreover, these devices show great potential for image recognition. Artificial neural network simulation has returned an image recognition accuracy of ~85%. All these findings show a great prospect of 2L-MoS2 for developing low power, transparent and flexible neuromorphic devices.

cond-mat.mtrl-sci↗

arXiv2026

Investigating the impact of copper-PEDOT:PSS matrix towards non-enzymatic electrochemical creatinine detection

Electrochemical creatinine sensors offer great promise towards rapid, reagent-free and point-of-care (POC) kidney-function monitoring. However, challenges related to analyte binding, data reproducibility, sensitivity, fouling and device degradation deter its widespread implementation. Here, we show how a carbon electrode modified with a combination of poly(3,4-ethylene dioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) and copper nanoparticles (CuNPs) can rapidly and accurately detect creatinine (CT) in artificial urine media employing electrochemical techniques. Applying redox potential sweeps (vs Ag/AgCl) using copper sulfate (CuSO4) solution on such sensor facilitates the CuNP embedding process inside the conjugated polymer matrix which has been further validated by supporting techniques. We predicted and validated the formation and contribution of two Cu-CT coordination complexes corresponding to Cu(I) and Cu(II) states, which are responsible for CT detection. The fabricated CT sensor exhibits high selectivity against major artificial urine interferents and is stable for a month showing minimal degradation (0.53%) in peak current value. Such sensors can be utilized to detect and monitor different stages of renal failure in real-time patient samples.

cond-mat.mtrl-sci↗

arXiv2023

Design, Modeling and Fabrication of Nanostructure Devices for Optoelectronic Applications

The current research work encompasses design modelling and fabrication of vertically aligned nanowire metal oxide semiconductor based voltage tunable quantum dot devices for optoelectronic applications. A novel device scheme is proposed for developing such VTQDs by combining the effects of nanowire geometry dependent structural confinement in transverse directions and the voltage assisted surface quantization in longitudinal direction. The formation of VTQDs near oxide/semiconductor interface at room temperature is predicted by developing a self consistent quantum electrostatic simultaneous solver. The photogeneration phenomenon and carrier transport in nanowire MOS based VTQD devices is analytically modelled by adopting non equilibrium Greens formalism based on second quantization field operators for incident photons and generated photocarriers. Engineering the combined effects of structural and electrical quantization has enabled a route for developing wavelength selective direct colour sensors with high spectral resolution. The developed NEGF based analytical model is further extended to obtain photocurrent which can be utilized for harvesting solar energy. A design window is also proposed for obtaining the desired values of solar cell performance parameters with the optimized device parameters such as, the nanowire diameter and oxide thickness. Finally, a patterned array of such nanowire MOS based VTQD devices is fabricated by employing electron beam lithography. The step like behaviour in capacitance voltage characteristics of such devices measured in situ within the FESEM chamber confirms the formation of VTQDs at room temperature. Such patterned nanowire MOS based VTQD devices can be utilized for the advanced photosensing and solar energy harvesting applications.

physics.app-ph↗

arXiv2020

Voltage tunable quantum dot array by patterned Ge-nanowire based metal-oxide-semiconductor (MOS) devices

Semiconductor quantum dots (QDs) are being regarded as the primary unit for a wide range of advanced and emerging technologies including electronics, optoelectronics, photovoltaics and biosensing applications as well as the domain of q-bits based quantum information processing. Such QDs are suitable for several novel device applications for their unique property of confining carriers 3-dimensionally creating discrete quantum states. However, the realization of such QDs in practice exhibits serious challenge regarding their fabrication in array with desired scalability and repeatability as well as control over the quantum states at room temperature. In this context, the current work reports the fabrication of an array of highly scaled Ge-nanowire (radius ~25 nm) based vertical metal-oxide-semiconductor devices that can operate as voltage tunable quantum dots at room temperature. The electrons in such nanowire experience a geometrical confinement in the radial direction, whereas, they can be confined axially by tuning the applied bias in order to manipulate the quantum states. Such quantum confinement of electrons has been confirmed from the step-like responses in the room temperature capacitance-voltage (C-V) characteristics at relatively low frequency (200 kHz). Each of such steps has observed to encompass convolution of the quantized states occupying ~6 electronic charges. The details of such carrier confinement are analyzed in the current work by theoretically modeling the device transport properties based on non-equilibrium Green's function (NEGF) formalism.

cond-mat.mes-hall↗