Impact of transition metal dopants (V, Nb, and Ta) on armchair and chiral structured gallium nitride (Ga30N30) nanotubes: A comprehensive DFT study

Abstract

Recently nanotubes have drawn the attention of researchers because of their unique properties such as fast response, high sensitivity, small size, exceptional electron mobility, significant heat capacity, and voltage characteristics suitable for various technological applications. Owing to the success of former studies of different group III-V binary nanotubes, this study has been performed by using density functional theory (DFT) with the B3LYP functional and LanL2DZ basis set in Gaussian 09 to explore the impact of transition metals (TMs) Vanadium (V), Niobium (Nb), and Tantalum (Ta) on structural, electrical, thermodynamic, and optical properties of two different variants- armchair and chiral structured GaNNTs (Ga₃₀N₃₀) to understand their comparative behavioral changes. The study reveals that doping GaNNTs with V, Nb, and Ta significantly enhances structural stability, especially when replacing the Ga atom. This improved structural stability suggests the potential for tailoring their electronic and mechanical properties. Again, in the case of Nb doping, replacing the N atom increases surface area and enhances reactivity, indicating its potential application in sensor development. Moreover, IR spectroscopy predicts the possibility of the natural existence of energetic favorability of all dopant-modified nanotubes with distinct vibrational signatures. The electronic properties suggest armchair (3, 3) systems especially, Ga₂₉N₃₀-Nb and Ga₂₉N₃₀- Ta, possess bandgaps suitable for replacing silicon-based electronics. On the other hand, the chiral (5, 3) Ga₃₀N₃₀ systems, exhibit metallic or near-metallic behavior with a bandgap of 0.2–0.4 eV, opening new avenues for material design. Also, the thermodynamic study demonstrates a correlation between Ga-site substitution and increased exothermicity during doping. Furthermore, the armchair (3, 3) Ga₃₀N₃₀ systems exhibit higher structural ordering after doping than the chiral (5, 3) Ga₃₀N₃₀ systems. Additionally, distinct UV-Vis absorption characteristics observed for both armchairs (3, 3) Ga₃₀N₃₀, and Ga₃₀N₂₉-Ta indicate their promising potential for optoelectronic, photodetectors, and photovoltaic applications. Considering all factors, armchair (3, 3) pristine and doped nanotubes have the potential for real-world applications, particularly in emerging technologies like supercapacitors, optoelectronic sensors, gas sensing devices, biosensors, and energy storage devices.