Programme

P.17 -- Posters, VCTP-50

Date: Tuesday, 5 August 2025

Time: 08:30 - 10:00

Diverse electronic and magnetic properties of silicon-doped graphene nanoribbons: A hybrid functional study

Duy Khanh Nguyen(1,2), To Vinh Bao (3)

(1) Laboratory for Computational Physics, Institute for Computational Science and Artificial Intelligence, Van Lang University, Ho Chi Minh City, Vietnam (2) Faculty of Mechanical - Electrical and Computer Engineering, School of Technology, Van Lang University, Ho Chi Minh City, Vietnam (3) Institute of Information Technology Training and Digital Transformation, Thu Dau Mot University, Binh Duong Province, Vietnam

In this work, using spin-polarized density functional theory (DFT) calculations with HSE06 hybrid functional, the structural, electronic, and magnetic properties of silicon (Si)-doped armchair and zigzag graphene nanoribbons (AGNRs and ZGNRs) are fully revealed. Pristine AGNRs belong to a nonmagnetic semiconductor with a direct bandgap of 1.92 eV. Under various Si substitutions, nonmagnetic bandgaps are tuned at 1.87, 1.84, 1.45, 1.71, 1.05, and 3.0 eV in the single Si edge-, single Si non-edge-, double Si ortho-, double Si meta-, double Si para-, and 100% Si-substituted AGNR configurations, respectively. Meanwhile, pristine ZGNRs displayed antiferromagnetic semiconducting behavior with a spin degenerate bandgap of 0.81 eV and becomes a ferromagnetic semimetal in the single Si configurations or an unusual ferromagnetic semiconductor in the 100% Si configuration. Under the developed DFT theoretical framework, the formation of quasi π (C-2pz and Si-3pz) and quasi σ (C-2s, C-2pxy and Si-3s and Si-3pxy) bands are identified in the Si-substituted configurations. These quasi π and quasi σ bands show weak separation, resulting in weak quasi sp2 hybridization in Si-C bonds, in which the identified hybridization mechanism are a strong evidence for the formation of stable planar 1D structures in the Si-substituted configurations. Our complete revelation of the essential properties of Si-substituted GNRs can provide a full understanding of their chemically doped 1D materials for various practical applications.

Presenter: Nguyen Duy Khanh