Morphology-controlled epitaxial vanadium dioxide low-dimensional structures: the delicate effects on the phase transition behaviors

Abstract

As an important strongly correlated electron material, VO2 undergoes a metal-insulator transition (MIT) accompanied by a huge change of several orders of magnitude in conductance and transmittance. The MIT behavior can be controlled by low-dimensional structures (LDSs) and the interaction between LDSs and substrates. Consequently, fabricating the LDSs and understanding the phase transition behaviors have great significance for the investigation of fundamental properties and applications. Using the pulsed laser deposition technique, we fabricate abundant LDSs (i.e., from zero-dimensional nanodots, one-dimensional nanowires, nanobelts and nanorods to two-dimensional nanoplatelets and ultra-thin films, and zero-/one-/two-dimensional mixed structures), and investigate the controllability of each deposition factor on the growth of the LDSs. TEM results confirm the high crystallinity of the as-synthesized LDSs. AFM results and ab initio calculations demonstrate the great influence of substrates on the growth orientation of the LDSs. More importantly, we systematically investigate the phase transition characteristics of the LDSs by temperature-dependent Raman spectroscopy and XRD. The results clearly reveal the structural dependence of the phase transition features due to the delicate effects of substrates and structures. Our technique provides a rapid, controllable and easy method for fabricating VO2 LDSs, which can lead to a deeper understanding of the electrical, optical, and magnetic properties and potential applications of VO2.

Recent Progress on Vanadium Dioxide Nanostructures and Devices: Fabrication, Properties, Applications and Perspectives

“…Driven by the advanced instruments and techniques for the growth of materials, the growth of VO 2 has made great progress during the past decades. As a transition metal element, vanadium contains several valence states, e.g., V 2+ , V 4+ and V 5+ [3,16,36]. The vanadium element in VO 2 is +4 valence; thus, it is easy to be oxidized in the process of preparation and to get mixed VO 2 /V 2 O 5 products with +4 and +5 valences.…”

“…In our previous work, by controlling the deposition conditions (e.g., substrate, oxygen pressure, deposition and annealing temperatures, pulse count and energy of laser, the distance between the target and substrate, etc. ), numerous LDSs of 0D NDs, 1D NWs, NBs and NRs; two-dimensional (2D) nanoplatelets; ultra-thin films; and also various mixed structures were fabricated [16]. Figure 14a ).…”

“…As we know, the MIT temperature and behavior of VO 2 are extremely sensitive to external stimuli, including doping, strain, surface/interface effects, electrochemical gating, electric field, light, electron beam, etc. [6,[14][15][16][17][18][19][20]. Besides, the morphology also has a great influence on the properties of VO 2 material.…”

Synthesis, metal–insulator transition, and photoresponse characteristics of VO2 nanobeams via an oxygen inhibitor-assisted vapor transport method

“…These findings demonstrate the high crystallinity and the axial growth direction [100] of the monoclinic VO 2 NBs. 47…”

“…These findings demonstrate the high crystallinity and the axial growth direction [100] of the monoclinic VO 2 NBs. 47 To verify the applicability of the oxygen inhibitor-assisted vapor-transport process, further attempts were made with 0.5 sccm O 2 on c-cut sapphire substrate with a specific orientation (11)(12)(13)(14)(15)(16)(17)(18)(19)(20), as shown Fig. 1(d).…”