arXiv subjects

Biswajit Khan

Publications and source records attributed to Biswajit Khan.

2 recordsLinked to original sources

arXiv2025

Engineering 2D Van der Waals Electrode via MBE Grown Weyl Semimetal 1T-WTe2 for Enhanced Photodetection in InSe

Achieving low contact resistance in advanced quantum electronic devices remains a critical challenge. With the growing demand for faster and energy-efficient devices, 2D contact engineering offers a promising solution. Beyond graphene, 1T-WTe2 has attracted attention for its excellent electrical transport, quantum phenomena, and Weyl semimetallic properties. Here, we demonstrate the direct wafer-scale growth of 1T-WTe2 via molecular beam epitaxy (MBE) and its use as a 2D contact for layered materials such as InSe. The 1T WTe2/InSe interface exhibits a barrier height nearly half that of conventional metal contacts, and its contact resistance is reduced by a factor of 21, effectively suppressing Fermi level pinning and enabling efficient electron injection. InSe/1T WTe2 photodetectors show broad photoresponsivity (0.14 to 217.58 A/W) under NIR to DUV illumination with fast rise/fall times of 42/126 ms, compared to lower responsivity (0.000865 A/W to 3.64 A/W) and slower response (150/144 ms) for InSe/Ti Au devices. The 1T WTe2/InSe devices thus exhibit approximately 60 times higher responsivity and 4 times faster response than conventional metal contacts. These results establish MBE-grown 1T-WTe2 as an effective 2D electrode, enhancing photodetection performance while simplifying device architecture, making it a strong candidate for next generation nanoelectronic and optoelectronic devices.

physics.optics↗

arXiv2024

Observation of room temperature gate tunable quantum confinement effect in photodoped junctionless MOSFET

In the pursuit of room temperature quantum hardware, our study introduces a gate voltage tunable quantum wire within a tri-gated n-type junctionless MOSFET. The application of gate voltage alters the parabolic potential well of the tri-gated junctionless MOSFET, enabling modification of the nanowire's potential well profile. In the presence of light, photogenerated electrons accumulate at the center of the junctionless nanowire, aligning with the modified potential well profile influenced by gate bias. These carriers at the center are far from interfaces and experience less interfacial noise. Therefore, such clean photo-doping shows clear, repeatable peaks in current for specific gate biases compared to the dark condition, considering different operating drain-to-source voltages at room temperature. We propose that photodoping-induced subband occupation of gate tunable potential well of the nanowire is the underlying phenomenon responsible for this kind of observation. This study reveals experimental findings demonstrating gate-induced switching from semi-classical to the quantum domain, followed by the optical occupancy of electronic sub-bands at room temperature. We developed a compact model based on the Nonequilibrium Green's function formalism to understand this phenomenon in our illuminated device better. This work reveals the survival of the quantum confinement effect at room temperature in such semi-classical transport.

cond-mat.mes-hall↗