arXiv subjects

Arindom Nag

Publications and source records attributed to Arindom Nag.

3 recordsLinked to original sources

arXiv2026

Vapor-liquid-solid growth of unconventional nanowires

Vapor liquid solid (VLS) growth is one of the most widely used routes for nanowire synthesis. For conventional semiconductor nanowires, here we refer to group IV and III-V systems, decades of work have established VLS growth across diverse vapor-phase methods and enabled substantial control over morphology, crystal phase, and structural modulation. In contrast, comparable deterministic control has not yet been achieved for many non-conventional nanowire classes, including oxides, carbides, and chalcogenides, despite their predicted functional properties and broad application potential. Here we survey and categorize the literature on VLS and VLS-related synthesis of these non-conventional nanowires, highlighting key similarities and differences relative to the group IV and III-V baseline. We analyze mechanistic and potential factors that underlie the lag in synthesis development, including constraints associated with precursor's chemistry and delivery, seed particle composition and dynamics, and competing non-catalytic nucleation and growth pathways. The review is grouped into three main sections, according to the order in which each step takes place during a nanowire growth process, namely precursor delivery, seed particle formation, and nucleation and growth. Each section starts with a brief discussion of what has been achieved in group IV and III-V nanowires as a baseline, followed by similar as well as unique aspects in other material classes. Each section concludes with challenges and opportunities, where we discuss how insights developed in one nanowire system can inform progress in others, ultimately paving the way for more deterministic synthesis and integration of complex one-dimensional nanomaterials.

cond-mat.mtrl-sci↗

arXiv2026

Synthesis and guided assembly of niobium trisulfide nanowires and nanowire chains by chemical vapor deposition

One-dimensional (1D) nanostructures of transition metal trichalcogenides (TMT) show unique properties through the combination of their anisotropic bonding and low dimensionality. Scalable synthesis approaches that enable control over the morphology, dimensions, and interfaces of 1D TMTs with other nanoscale materials could allow these properties to be used in novel devices. Here, we report chemical vapor deposition of a 1D TMT, namely niobium trisulfide (NbS3) in the form of nanowires, on different substrates, including bulk substrates (amorphous SiO2/Si and crystalline c-sapphire) and several two-dimensional (2D) van der Waals materials (graphene, h-BN, CrSBr). We demonstrate high growth yield with axial growth rates of up to 40 micrometer/min and with two different growth modes: short nanowires of rectangular cross-section, and unusual long, "chained nanowires" up to 100 micrometer in length with sawtooth morphology. We discuss a mechanism that accounts for the two morphologies and discuss how the structure can be tuned through substrate choice and growth conditions. We further demonstrate guided assembly at the edges of graphene and h-BN, as well as epitaxial growth on few-layer CrSBr and c-sapphire. These results open pathways to explore scalable synthesis and directed assembly of 1D TMT nanomaterials in unique morphologies.

cond-mat.mtrl-sci↗

arXiv2025

Ab initio prediction of strain-tunable spin defects in quasi-1D TiS3 and NbS3 nanowires

Defects in atomically thin van der Waals materials have recently been investigated as sources of spin-photon entanglement with sensitivity to strain tuning. Unlike many two-dimensional materials, quasi-one-dimensional materials such as transition metal trichalcogenides exhibit in-plane anisotropy resulting in axis-dependent responses to compressive and tensile strains. Herein, we characterize the tunable spin and optical properties of intrinsic vacancy defects in titanium trisulfide (TiS3) and niobium trisulfide (NbS3) nanowires. Within our ab initio approach, we show that sulfur vacancies and divacancies (VS and VD , respectively) in TiS3 and NbS3 adopt strain-dependent defect geometries between in-plane strains of -3 % and 3 %. The calculated electronic structures indicate that both VS and VD possess in-gap defect states with optically bright electronic transitions whose position relative to the conduction and valence bands varies with in-plane strain. Further, our calculations predict that VS in TiS3 and VD in NbS3 exhibit transitions in their ground state spins; specifically, a compressive strain of 0.4 % along the direction of nanowire growth causes a shift from a triplet state to a singlet state for the VS defect in TiS3, whereas a tensile strain of 2.9 % along the same direction in NbS3 induces a triplet ground state with a zero-phonon line of 0.83 eV in the VD defect. Our work shows that the anisotropic geometry of TiS3 and NbS3 nanowires offers exceptional tunability of optically active spin defects that can be used in quantum applications.

cond-mat.mtrl-sci↗