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Nano Materials and Devices Laboratory
(NANOMADE-LAB)
1. Novel 2D Materials beyond Graphene:
Since the discovery of graphene in 2004, two-dimensional (2D) materials have grown in importance in both academia and the semiconductor industry due to their remarkable electrical and optical properties. Semiconducting transition metal dichalcogenides, insulating boron nitride, weyl semimetals, and superconductors are among the materials now available in two dimensions. These 2D materials show great promise for a variety of unique applications that are not conceivable with bulk materials. To fully realize the potential of 2D materials, significant experimental and theoretical advancements in their growth and characterisation are required. Many growth strategies have been devised for the synthesis of two-dimensional materials on rigid and flexible substrates. However, there are still several concerns and challenges associated with the large-scale synthesis of particular 2D materials with high crystallinity. So, one of my focus is on synthesis of Novel Single Crystal 2D Materials and Characterization of 2D Materials with the help of different methods such as chemical vapor transport, Bridgman techniques, chemical vapor deposition, pulsed laser deposition, and solution growth.
Bridgman Method
Advanced Electronic Material, 2020, 6, 1900794.
1T MoTe2
2H MoTe2
MoSe2
MoS2
GeS
SnS2
InSe
Pulsed Laser Deposition
Quasi Nanoribbon MoS2
Chemical Vapor Deposition
Triangle MoS2
Advanced Materials, 2023, 2302469.
Slow Evaporation Constant Temperature
BA2FAPb2I7
N-MPDAPbBr4
Advanced Functional Materials, 2022, 32, 2112277.
2. 2D Materials as Field-Effect Transistors (FETs):
Scaling down problems could be resolved by using 2D materials as channels. Numerous two-dimensional materials, such as hexagonal boron nitride, black phosphorus, and transition metal dichalcogenides (TMDs), have been investigated since the discovery of graphene in 2004. These materials, in contrast to bulk silicon, display lattice periodicity in the plane, stringent quantum constraints on electron energy levels and wave functions, hence producing a quantized energy band structure. Carrier confinement, quantum tunneling, and tunable energy gaps are made possible by this quantum confinement. By varying parameters including layer number, heterostructures, external pressures, and electric fields, 2D materials lattice periodicity can be changed, which in turn can change the band structure and band gap size. Furthermore, the surface of 2D transistors is free of dangling bonds, which results in little change in carrier mobility with body thickness. This eliminates the necessity for lattice constant matching, simplifying integration with other materials. Extensive study into 2D device innovation, including transistors, memory devices, neuromorphic devices, and quantum-engineering devices, has been sparked by the special qualities of 2D materials.
InSe-FET
Nano Letters, 2014, 14, 2800-2806.
GeS-FET
Nanoscale, 2016, 8, 2284-2292.
InSnSe-FET
ACS Applied & Material Interfaces, 2019, 11, 24269-24278.
HfSSe-FET
Advanced Electronic Material, 2020, 6, 1900794.
Si2Te3-FET
Journal of Material Chemistry C, 2021, 9, 10478-10486.
4-Probe InSe-FET
Nano Letters, 2015, 15, 3815-3819.
3. 2D Materials as Efficient Photodetection:
We rely on photonic devices that convert light into electrical messages in many of our everyday interactions. Applications for these devices include motion tracking, gas sensing, optical communications, cyber security, biomedical imaging, and video imaging. Devices with novel photonic functions and their mass manufacture are urgently needed, but this can only happen if processing elevated materials becomes more efficient. With the increasing diversity of their application domains, photodetection technologies that excel in efficiency, speed, transparency, wavelength range, flexibility, and integrability are gaining significant importance. A two-dimensional material is a multi-layered substance in which chemical bonds hold the individual atoms together while van-der-Waal interactions connect atoms from different levels. The most promising semiconductor materials for the manufacture of optoelectronic devices are 2D materials with extraordinary properties with appropriately sized and layer-dependent bandgaps. 2D materials will become more superior in upcoming optoelectronic and nanophotonic devices by optimizing their surface and designing suitable device topologies.
InSe-FET
GeS-FET
Nano Letters, 2014, 14, 2800-2806.
Si2Te3-FET
Journal of Material Chemistry C, 2021, 9, 10478-10486.
BA2FAPb2I7-FET
1D N-MPDAPbBr4-FET
Materials Advances, 2022, 3, 8771-8779.
N-MPDAPbBr4-FET
Advanced Functional Materials, 2023, 2214078.
Nanoscale, 2016, 8, 2284-2292.
Advanced Functional Materials, 2022, 32, 2112277.
4. Assembly of van der Waals Materials:
The study of two-dimensional materials, or van der Waals (vdW) heterostructures, has advanced quickly since the development of the atomic layer transfer technique. The atomic layers that make up the vdW heterostructures are put together by vdW force and have the following unique characteristics: (1) there are many options of layered materials with different material properties; (2) the interface can be atomically flat, unaffected by the inter-diffusion and segregation of atoms; and (3) different 2D materials can be stacked in the desired order without the restriction of lattice matching. Graphene was first studied by exfoliating it on a SiO2/Si substrate. This process hampered graphene inherent qualities because the SiO2 surface had surface roughness and charged impurities. Hexagonal boron nitride (h-BN) was suggested as a solution to this issue in place of the SiO2/Si substrate. The multilayer insulator h-BN has a large bandgap and offers graphene an atomically flat basis to significantly increase the carrier mobility in graphene. As a result, physical properties of graphene, namely ballistic transport, were observed as well as the fractional quantum Hall effect (QHE). Furthermore, two-dimensional (2D) materials exhibit the characteristics of flexible films that are anticipated to be applied onto abundant structures and devices. This would enable hybrid structures and devices to exploit the exceptional optical, electrical, and mechanical properties of the two-dimensional (2D) materials.
van der Waals Stacking
InSe/h-BN/GeS
ACS Applied & Material Interfaces, 2020, 12, 26213-26221.
SnS2/GaSe
SnS2/ZrS3
Applied Surface Science, 2021, 535, 147480.
Stacking Equipment
5. 2D Flexible Nanoelectronics:
The exceptional characteristics of 2D crystals have sparked significant attention in both traditional semiconductor technology and emerging flexible nanotechnology. This is due to the fact that, among other things, these atomic sheets provide the ability to scale the thickness to the desired level, which is crucial in numerous critical material categories such as semiconductors, insulators, transparent conductors, and transducers. Particularly, the advancement of 2D crystals holds significant potential for flexible nanoelectronics due to their unparalleled combination of device mechanics and device physics that can be achieved on soft polymeric or plastic substrates. This can facilitate the production of economically feasible large-area high-performance flexible devices that have been long desired. Consequently, it is anticipated that current flexible technology, which presently serves as inexpensive commodity applications like sensors and radio-frequency identification tags, will evolve into integrated nanosystems boasting electronic capabilities similar to those of silicon devices. Furthermore, these nanosystems will possess manufacturing form factors and mechanical flexibility that surpass the capabilities of conventional semiconductor technology. Thus, a new era is dawning in integrated flexible technology that is predicated on 2D crystals.
InSe
Nano Letters, 2014, 14, 2800-2806.
HfSSe
InSnSe
ACS Applied & Material Interfaces, 2019, 11,
24269-24278.
Advanced Electronic Material, 2020, 6, 1900794.
InSe/WSe2
ACS Nano, 2021, 15, 8686-8693.
BA2FAPb2I7
Advanced Functional Materials, 2022, 32, 2112277.
6. 2D Materials for Photovoltaics:
The use of 2D nanomaterials in the creation of solar cells has enormous potential for the advancement of renewable energy technology. Some of the special benefits of 2D nanostructures include their high optical transparency, high absorption, tunable band gap, mobility, charge carrier lifetimes, and flexibility. Numerous atomically thin layered materials, such as graphene, h-BN, transition metal dichalcogenides (TMDs-MoS2, WSe2, etc.), MXenes (Ti3AlC2), BP, and silicene, have been made possible by recent advancements in this field. The critical requirements of third-generation solar cells, including effective photon absorption, a broad electronic band structure, the creation and segregation of charge carriers, steady performance, sustainability, and scalability, are satisfied by these material systems. Compared to the single-crystalline and thin-film semiconductors utilized as the active layers in the earlier generation of PV cells, several of these properties are much superior. For example, monolayer graphene has demonstrated the highest optical transparency known to science, absorbing only 2.3% of incident light in the visible spectrum while having a negligible reflectance of ∼0.3%. Comparatively, an equal Si thickness of about 20 nm is the only way to achieve the same optical transparency metric, which has limitations for practical development. This has opened the door for graphene to perhaps replace ITO transparent conductors in solar cells. The customizable electrical characteristics of semimetals, semiconductors, and superconductors make 2D TMDs appealing choices. MoS2 in bulk has an indirect band gap of 1.3 eV, whereas in its ultrathin monolayer form, it has a direct band gap of 1.8 eV. These characteristics enable MoS2 to be used as an active ingredient in photovoltaic cells, as its optical absorption is between 5% and 10%. The performance of these PVs is improved by the addition of 2D materials because of their special structure and characteristics.
0D MoS2/2D InSe
GaSe/SnS2
Applied Surface Science, 2021, 535, 147480.
Advanced Material Interfaces, 2019, 6, 1801336.
7. Perovskite Random Lasing:
Random lasers exhibit several advantages as compared to conventional lasers, which require a gain medium to amplifythe light and an optical cavity for the amplification to beefficient. In contrast, a random laser does not require a separate medium; the material itself acts as a gain medium for optical feedback. The gain is provided by the scattering of light which occurs due to the randomness. The light candiffuse and randomly forms closed loops by constructive interference to realize the lasing modes. The major advantage of random lasers lies in their inexpensive and relatively simple technology compared to that of regular lasers. The properties that make random lasers special compared to regular lasers are their color and angular dependence over the complete solid angle of 4π, which makes them ideal candidates for display applications. In addition, random lasers have a unique characteristic, namely the coexistence of high temporal coherence and low spatial coherence, which makes random lasers an ideal light source for speckle-free imaging.
N-MPDAPbBr4
Nanoscale, 2020, 12, 18269-18277.
Advanced Functional Materials, 2023, 2214078.
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