A new precursor route for the growth of NbO₂ thin films by chemical vapor deposition

Abstract

Niobium dioxide (NbO2) exhibits metal-insulator transition (Mott transition) and show the potential for application in memristors and neuromorphic devices. Presently growth of NbO2 thin films requires high-temperature reduction of Nb2O5 films using H2 or sophisticated techniques such as molecular beam epitaxy and pulsed laser deposition. The present study demonstrates a simple chemical route of the direct growth of crystalline NbO2 films by chemical vapor deposition (CVD) using a freshly prepared Nb-hexadecylamine (Nb-HDA) complex. X-ray diffraction studies confirm the NbO2 phase with a distorted rutile body-centered-tetragonal (BCT) structure and the film grown with a highly preferred orientation on c-sapphire. X-ray photoelectron spectroscopy (XPS) confirms the +4 oxidation state. The present method offers facile growth of NbO2 films without post-reduction steps which will be assumed to be a cost-effective process for NbO2 based devices.

NbO2 a Highly Stable, Ultrafast Anode Material for Li- and Na-Ion Batteries

“…The appearance of XPS peaks at 204.7 and 206.8 eV indicates Nb is in the +4 oxidation state, suggesting the formation of NbO 2 . , Along with that, there are additional peaks at 207.8 and 210.4 eV corresponding to the 3d 5/2 and 3d 3/2 of Nb 2 O 5 . It is documented in the literature that NbO 2 is a strong reducing agent and is prone to oxidize to Nb 2 O 5 rapidly, even under high vacuum conditions suggesting that it is extremely difficult to characterize pure Nb (+4) state …”

“…It is documented in the literature that NbO 2 is a strong reducing agent and is prone to oxidize to Nb 2 O 5 rapidly, even under high vacuum conditions suggesting that it is extremely difficult to characterize pure Nb (+4) state. 25 Further, microscopic characterizations have been carried out to study the morphology of the synthesized NbO 2 . Figure 1c shows a low-magnification TEM image of NbO 2 having nanoparticle morphology with size distribution ranging from 10 to 40 nm.…”

“…NbO 2 was synthesized using a similar protocol to the previously reported literature. 25 Briefly, 1 mL of 4 mmol of niobium (V) ethoxide was dispersed in 30 mL of H 2 O 2 solution. In 5 mL of ethanol, 3.76 g of HDA (15 mmol) was dispersed at 70 °C.…”

Synthesis, characterisation, electrocatalytic HER activity, and electrical resistivity of 3R-NbS2 nanosheets

“…The condensation of the peroxo niobium complex and intercalation of HDA (hexadecylamine) occur simultaneously through the interaction between negatively charged niobium oxide layers and protonated HDA molecules, leading to the formation of a foam of the Nb-HDA complex. [22][23][24]26 Finally, 3R-NbS 2 nanosheets were formed by reacting Nb-HDA foam with H 2 S gas in a N 2 atmosphere.…”

“…A procedure similar to one that has been reported recently was followed to prepare the Nb–HDA complex. 26 The Nb–HDA complex was synthesized using niobium( v ) ethoxide (Nb(OC 2 H 5 ) 5 . 99.95%, Sigma Aldrich), hydrogen peroxide (30%, H 2 O 2 ), and 1-hexadecylamine (C 16 H 33 NH 2 , HDA) in a Borosil glass beaker (Scheme 1a).…”