Metalorganic chemical vapor deposition of highly oriented thin film composites of V₂O₅ and V₆O₁₃: Suppression of the metal–semiconductor transition in V₆O₁₃

Abstract

Thin films of vanadium oxides were grown on fused quartz by metalorganic chemical vapor deposition using vanadyl acetylacetonate as the precursor. Growth at temperatures ⩾560 °C results in composites of strongly (00l)-oriented V2O5 and V6O13. The dominant phase of the film changes from V2O5 to V6O13, and back to V2O5, as the growth temperature is raised from 560 to 570 °C, then to 580 °C, as evidenced by x-ray diffraction and Rutherford backscattering analyses. This reentrant-type growth trend was interpreted on the basis of the small difference in the free energy of formation of V2O5 and V6O13 and the presence of metal–oxygen bonds in the precursor. In contrast with single-crystalline V6O13, the film predominantly composed of highly oriented single-crystalline platelets of V6O13 did not undergo the semiconductor–metal transition at −123° K, despite the connectivity being well above the percolation threshold. Instead, a semiconductor-to-semiconductor transition was observed in this film, which is explained in terms of the observed relaxation of the edges of all the platelets of metallic V6O13 to semiconducting V2O5.

Advances in thermochromic vanadium dioxide films

“…Low-pressure CVD (LPCVD) has also been used to deposit thin lms of VO 2 onto glass substrates. 116,117 This work demonstrated that variations in the characteristics of the phase transition were a function of lm microstructure. The lms were very dense at 475 C and showed a large change in resistance at 66 C, displaying a small temperature hysteresis in the transition.…”

Phase Control of Multivalent Vanadium Oxides VOx by Ion‐Beam Sputter‐Deposition

“…Thin films of the various vanadium oxides have been deposited by various techniques such as evaporative methods, [23,24] sputtering processes, [25][26][27] chemical vapor deposition, [28] atomic layer deposition, [29,30] pulsed laser deposition (PLD), [31,32] and hydrothermal synthesis. [33] In all cases, the formation of a specific phase can be selected in the growth process by adjusting the growth parameters.…”

Thermochromic Thin Films and Nanocomposites for Smart Glazing

“…Takahshi et al [112] used vanadyl tri(isobutoxide) VO(0-i-Bu) 3 as a single source precursor for depositing V0 2 thin films by dip-coating, as well as MOCVD at low pressure onto glass substrates, which resulted in discontinuous thin films with fine needle-like V0 2 crystals. Lowpressure CVD (LPCVD) has also been used to deposit thin films of V0 2 onto glass substrates [113,114]. This work demonstrated that variations in the characteristics of the phase transition were a function of film microstructure.…”