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Kaustuv Banerjee

Publications and source records attributed to Kaustuv Banerjee.

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Are gate-all-around 2D CFETs the optimal architecture for the A2 node and beyond?

As logic scaling enters the angstrom era, vertically stacked complementary field-effect transistors (CFETs) based on atomically thin two-dimensional (2D) semiconductors offer a potential route to extend device scaling beyond the A2 node. Here, we develop an A2-oriented 2D CFET integration flow with a CPP of 36 nm and Lg of 10 nm and present initial demonstrations of several key process modules. Despite their atomically thin channels, 2D GAA CFETs do not provide a contacted poly pitch scaling advantage over Si GAA CFETs at the A2 node, because contact formation constraints impose a similar minimum CPP of 36 nm. We also combine a critical assessment with a multiscale power-performance-area (PPA) evaluation framework spanning quantum transport simulations, compact-model generation, A2-targeted 2D CFET gate-all-around (GAA) integration-flow definition, parasitic extraction and circuit-level benchmarking. Our analysis, however, shows that the expected benefits of 2D GAA CFETs are strongly constrained by non-idealities, in particular high contact resistance and dominant layout-induced parasitic capacitances. Although architectural optimization can improve the Ieff/Ceff ratio, the associated rise in absolute capacitance limits circuit-level gains. Meaningful progress will require co-optimization of contacts, transport and parasitics, together with 2D-specific CFET architectures.

physics.app-ph

Nonlinear Strain-Mediated Magnetoelectric Coupling in Sub-Microscale Ni/BPZT Thin-Film Devices

Strain-mediated magnetoelectric (ME) heterostructures enable electric-field control of magnetism and are promising for ultra-low-power spintronic logic. Yet achieving spatially selective, low-voltage control in thin films and quantifying ME coupling across the full ferroelastic loop remains challenging. Here, we investigate sub-micrometer Ni/BPZT thin-film devices with laterally patterned gates that localize in-plane strain beneath the Ni stripe and modulate its magnetization. We use anisotropic magnetoresistance to measure magnetization changes across the ferroelastic loop under different magnetic bias fields. Combined with Multiphysics strain simulations and micromagnetic modeling, this provides a quantitative framework that captures the convolution of ferroelastic and magnetoelastic nonlinearities and provides critical insight for device design, while enabling multi-state, bias-field-free magnetization control for non-conventional computing. The extracted coupling coefficient in linear range is 1.3 mT/V across a 700 nm gap, with a clear pathway to improving voltage efficiency through device scaling, establishing a scalable CMOS-compatible platform for energy-efficient spintronic devices.

physics.app-ph

Electronic Characterization of a Charge-Transfer Complex Monolayer on Graphene

Organic charge-transfer complexes (CTCs) formed by strong electron acceptor and strong electron donor molecules are known to exhibit exotic effects such as superconductivity and charge density waves. We present a low-temperature scanning tunneling microscopy and spectroscopy (LT-STM/STS) study of a two-dimensional (2D) monolayer CTC of tetrathiafulvalene (TTF) and fluorinated tetracyanoquinodimethane (F4TCNQ), self-assembled on the surface of oxygen-intercalated epitaxial graphene on Ir(111) (G/O/Ir(111)). We confirm the formation of the charge-transfer complex by dI/dV spectroscopy and direct imaging of the singly-occupied molecular orbitals. High-resolution spectroscopy reveals a gap at zero bias, suggesting the formation of a correlated ground state at low temperatures. These results point to the possibility to realize and study correlated ground states in charge-transfer complex monolayers on weakly interacting surfaces.

cond-mat.mes-hall

Two-dimensional band structure in honeycomb metal-organic frameworks

Metal-organic frameworks (MOFs) are an important class of materials that present intriguing opportunities in the fields of sensing, gas storage, catalysis, and optoelectronics. Very recently, two-dimensional (2D) MOFs have been proposed as a flexible material platform for realizing exotic quantum phases including topological and anomalous quantum Hall insulators. Experimentally, direct synthesis of 2D MOFs has been essentially confined to metal substrates, where the interaction with the substrate masks the intrinsic electronic properties of the MOF. Here, we demonstrate synthesis of 2D honeycomb metal-organic frameworks on a weakly interacting epitaxial graphene substrate. Using low-temperature scanning tunneling microscopy (STM) and atomic force microscopy (AFM) complemented by density-functional theory (DFT) calculations, we show the formation of 2D band structure in the MOF decoupled from the substrate. These results open the experimental path towards MOF-based designer quantum materials with complex, engineered electronic structures.

cond-mat.mtrl-sci

Molecular Assembly on Two-Dimensional Materials

Molecular self-assembly is a well-known technique to create highly functional nanostructures on surfaces. Self-assembly on two-dimensional materials is a developing field and has already resulted in the discovery of several rich and interesting phenomena. Here, we review this progress with an emphasis on the electronic properties of the adsorbates and the substrate in well-defined systems, as unveiled by scanning tunneling microscopy (STM). We cover three aspects of the self-assembly. The first one focuses on non-covalent self-assembly dealing with site-selectivity due to inherent moire pattern present on 2D materials deposited on substrates. Modification of intermolecular interactions and molecule-substrate interactions influences the assembly drastically and 2D materials can also be used as a platform to carry out covalent and metal-coordinated assembly. The second part deals with the electronic properties of molecules adsorbed on 2D materials. By virtue of being inert and possessing low density of states near the Fermi level, 2D materials decouple molecules electronically from the underlying metal substrate and allow high-resolution spectroscopy and imaging of molecular orbitals. The moire pattern on the 2D materials causes site-selective gating and charging of molecules in some cases. The last section covers the effects of self-assembled organic molecules on the electronic properties of graphene as revealed by spectroscopy and electrical transport measurements. Non-covalent functionalization of 2D materials has already been applied for their application as catalysts and sensors. With the current surge of activity on building van der Waals heterostructures from 2D materials, molecular self-assembly has the potential to add an extra level of flexibility and functionality for applications ranging from flexible electronics and OLEDs to novel electronic devices and spintronics.

cond-mat.mes-hall