| Summary: | The present study highlights the significant impact of trace level doping of boron in titanium dioxide (TiO2) nanotubes by investigating the structural, optical and electronic properties of samples, TNT and B-TNT. TEM analysis of boron-doped sample confirms the formation of crystalline nanotube structures and the trace level quantification of boron was confirmed by XPS analysis, where B shows feature of Ti–O–B bonding. Raman analysis revealed that the rutile phase becomes prominent after boron doping and Raman bands shift towards higher wavenumber was observed with increase in the tube diameter. The boron incorporation in TiO2 nanotubes reduces the band gaps from 3.3 eV to 3.1 eV and the mid-gap states were created within the band gap of the B-TNT sample. The change in valance band position from 2.5 eV to 2.9 eV after boron doping significantly changed the Fermi level position in TiO2 nanotubes. The work function of pristine and boron doped TiO2 samples are observed as 4.23 eV and 4.27 eV, respectively, as measured by Kelvin probe force microscopy. Here, we have investigated the band alignment of TNT and B-TNT by using state-of-the-art material characterization surface sensitive techniques. It can also be concluded that the electron affinity of the B-TNT sample is enhanced ∼4.07 eV than that of TNT ∼ 3.43 eV. The type –II band alignment is observed to be in between TNT and B-TNT with a valence band offset (VBO) ∼ 0.4 eV and conduction band offset (CBO) ∼ 0.6 eV. Keywords: Nanotubes, Boron-doping, Surface potential, Fermi level position, Band alignment, Electron affinity
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