Browsing by Author "Baishali Thakurta"

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Application of a microwave synthesized ultra-smooth a-C thin film for the reduction of dielectric/semiconductor interface trap states of anoxide thin film transistor
(Royal Society of Chemistry, 2022) Nila Pal; Baishali Thakurta; Rajarshi Chakraborty; Utkarsh Pandey; Vishwas Acharya; Sajal Biring; Monalisa Pal; Bhola N. Pal
In high-κ dielectric-based thin-film transistors (TFTs), tailoring the surface of the gate dielectric layer is a crucial issue for the improvement of the device performance. Herein, a simple solution-processed ultra-smooth amorphous-carbon (a-C) film is applied as a surface modification layer on the top of the high-κ ion-conducting Li-Al2O3 dielectric of a bottom gated SnO2 TFT. The a-C film minimizes the surface roughness of the gate dielectric and forms a strong coordination bond between the doped nitrogen of the a-C film and tin (Sn) of the upper lying SnO2 semiconducting channel, which lowers the gate leakage current, carrier scattering and trap state density at the dielectric/semiconductor interface successfully. As a consequence, the TFT with an a-C interface shows an improvement in the carrier mobility by 6.7 times with a higher ON/OFF ratio and a lower subthreshold swing (SS) by 3.8 times. An optimized device with an a-C gate interface shows a saturation carrier mobility, ON/OFF ratio and SS value of 21.1 cm2 V−1 s−1, 7.0 × 104, and 147 mV dec−1, respectively. Moreover, a significant improvement in the cycling electrical stability has been observed which is an outcome of a reduced trap state of an a-C modified TFT. © 2022 The Royal Society of Chemistry.
One-Step Room Temperature Synthesis of Printable Carbon Quantum Dots Ink for Visual Encryption and High-Performance Photodetector
(John Wiley and Sons Inc, 2024) Baishali Thakurta; Sobhan Hazra; Alapan Samanta; Adnan Nasir; Amresh Kumar Singh; Deepak Maurya; Bama Charan Mondal; Anupam Giri; Bhola Nath Pal; Monalisa Pal
Carbon quantum dots (CQDs) have emerged as promising materials for optoelectronic applications and have garnered much interest as potential competitors to conventional inorganic or hybrid semiconductor quantum dots because of carbon's intrinsic merits of high stability, low cost, and environment-friendliness. The ability of easy formulation of functional ink of CQDs is necessary for the development of industrial-scale, reliable, inexpensive printing/coating processes, for its full exploitation in the ever-growing class of applications in sensors, optoelectronics, and energy storage and conversion. Here a facile one-step room-temperature synthesis of printable, fluorescent CQD ink is demonstrated. The as-synthesized fluorescent CQD ink is used for invisible fingerprint stamps, printing of micro-patterns, and soft lithographic patterning with a resolution down to 1.5 µm. This functional CQD ink is also used to fabricate a high-performance CQD-ZnO heterojunction ultraviolet (UV) photodetector with a photo-responsivity of 3.85 A W−1, detectivity of 6.78 × 1010 Jones, and an external quantum efficiency (EQE) of 15.3%. The enhanced device performance can be attributed to CQD's high photocurrent generation efficiency and rational combination of the asymmetric electrode materials. This work enables a high-temperature stable CQD fluorescent ink synthesis method to fulfill the processing requirements of printing and soft lithographic patterning for visual encryption and optoelectronics. © 2024 Wiley-VCH GmbH.
Wafer scale growth of single crystal two-dimensional van der Waals materials
(Royal Society of Chemistry, 2024) Chetna Gautam; Baishali Thakurta; Monalisa Pal; Anup Kumar Ghosh; Anupam Giri
Two-dimensional (2D) van der Waals (vdW) materials, including graphene, hexagonal boron nitride (hBN), and metal dichalcogenides (MCs), form the basis of modern electronics and optoelectronics due to their unique electronic structure, chemical activity, and mechanical strength. Despite many proof-of-concept demonstrations so far, to fully realize their large-scale practical applications, especially in devices, wafer-scale single crystal atomically thin highly uniform films are indispensable. In this minireview, we present an overview on the strategies and highlight recent significant advances toward the synthesis of wafer-scale single crystal graphene, hBN, and MC 2D thin films. Currently, there are five distinct routes to synthesize wafer-scale single crystal 2D vdW thin films: (i) nucleation-controlled growth by suppressing the nucleation density, (ii) unidirectional alignment of multiple epitaxial nuclei and their seamless coalescence, (iii) self-collimation of randomly oriented grains on a molten metal, (iv) surface diffusion and epitaxial self-planarization and (v) seed-mediated 2D vertical epitaxy. Finally, the challenges that need to be addressed in future studies have also been described. © 2024 The Royal Society of Chemistry.
Wafer-scale synthesis of two-dimensional ultrathin films
(Royal Society of Chemistry, 2023) Amresh Kumar Singh; Baishali Thakurta; Anupam Giri; Monalisa Pal
Two-dimensional (2D) materials, consisting of atomically thin layered crystals, have attracted tremendous interest due to their outstanding intrinsic properties and diverse applications in electronics, optoelectronics, and catalysis. The large-scale growth of high-quality ultrathin 2D films and their utilization in the facile fabrication of devices, easily adoptable in industrial applications, have been extensively sought after during the last decade; however, it remains a challenge to achieve these goals. Herein, we introduce three key concepts: (i) the microwave assisted quick (∼1 min) synthesis of wafer-scale (6-inch) anisotropic conducting ultrathin (∼1 nm) amorphous carbon and 2D semiconducting metal chalcogenide atomically thin films, (ii) a polymer-assisted deposition process for the synthesis of wafer-scale (6-inch) 2D metal chalcogenide and pyrolyzed carbon thin films, and (iii) the surface diffusion and epitaxial self-planarization induced synthesis of wafer-scale (2-inch) single crystal 2D binary and large-grain 2D ferromagnetic ternary metal chalcogenide thin films. The proposed synthesis concepts can pave a new way for the manufacture of wafer-scale high quality 2D ultrathin films and their utilization in the facile fabrication of devices. © 2024 The Royal Society of Chemistry.