Optical and electrical properties of sputtered vanadium oxide films

Abstract

Electrical and optical properties of sputtered amorphous vanadium oxide thin films

Correlation between in situ structural and optical characterization of the semiconductor-to-metal phase transition of VO2 thin films on sapphire

“…The best fit allows to find n C = 2.3 + 0.2i in the semiconductor phase, and n H = 3.6 + 3.2i in the metallic phase (corresponding to the minimum error respectively of 1.5% and 0.5%). Although n C might seem a low value for vanadium dioxide, it is rather consistent with the wide range of values found in literature where VO 2 optical constants exhibit strong differences depending on the deposition technique, 20,[63][64][65][66][67][68][69][70][71] the substrate temperatures 63 and the oxygen pressure 64 employed during the deposition process. Once all the optical properties are found, then IR reflectance, transmittance and emissivity of any VO 2 /sapphire structure can be easily simulated and optimized as a function of VO 2 film thickness.…”

Photothermal Characterization of Thermochromic Materials for Tunable Thermal Devices

“…(a) First, we calculated the average optical constants of vanadium dioxide, far from the SMT, in both the semiconductor state (at 30 • C), and in the metallic state (at 90 • C) by the simultaneous fit of the transmittance (T r ) and the front and rear reflectances (R f , and R r ), assuming that the silicon refractive index is n Si = 3.43, Although this method is rather inaccurate to retrieve the refractive index for nanolayers, with respect to ellipsometry, the best fit values found for the semiconductor phase (n S + ik S = 2.7 + i0.04), and for the metallic phase (n M + ik M = 2.9 + i4.8) are in agreement with the wide range of values reported in the literature for (2 µm to 3 µm) [19][20][21][22][23][24][25][26] depending on the different fabrication process (for rf sputtering Tazawa et al [24] found n M + ik M = 2.8 + i4.4). It is worth noting that our values were retrieved without using any effective medium approximation to simulate the surface roughness or [22,27].…”

Anomalies in stiffness and damping of a 2D discrete viscoelastic system due to negative stiffness components

“…We claim that the heterogeneity required to achieve a balance between positive and negative stiffness phases might be obtainable using microlithography or nanolithography, as described in [20]. Alternatively, one can manufacture a film containing nano-grain inclusions of phase transforming material, such as VO 2 , through sputtering deposition [21] or pulsed laser deposition [22].…”