Effect of oxygen partial pressure on the structural and optical properties of dc reactive magnetron sputtered molybdenum oxide films

Hybrid co-deposition of mixed-valent molybdenum–germanium oxides (MoxGeyOz): A route to tunable optical transmission

“…14 are significantly lower than that of their bulk constituents [37,64,[71][72][73]. The discrepancy between bulk densities for GeO 2 and MoO 3 and those of the as-deposited films can be attributed to no heating being applied to the substrate during deposition as well as the tendency of oxygen to act as a grain refining agent, interrupting nucleation and leading to high defect and interface volumes [65][66][67].…”

Molybdenum Oxides Deposited by Modulated Pulse Power Magnetron Sputtering: Stoichiometry as a Function of Process Parameters

“…The presence of oxidation state Mo 6+ was indicative of the compound MoO 3 , while the presence of Mo 5+ and Mo 4+ was associated with substoichiometric compounds including Mo 2 O 5 and MoO 2 (Table I). 2,20,21,43,67,[68][69][70][71] Furthermore, at f O 2 ð Þ < 1.00 sccm, metallic Mo was also present. It is highly likely that small quantities of additional suboxides were present within the films; however, their presence was indistinguishable from the uncertainty inherent in the peak fitting process.…”

“…In its fully oxidized state (VI), molybdenum trioxide (MoO 3 ) is optically transparent with a band gap that ranges from 2.67 eV to 3.12 eV. 5,9,20 MoO 3 also exhibits dynamic coloration via reduction induced by UV irradiation (photochromism), 5,9 charge injection (electrochromism), 9,21 or heat treatment (thermocoloration). 22 Additional oxide compounds formed by molybdenum include the ''surface phase'' Mo 2 O 5 (Mo(V)), which has no known bulk structure, [23][24][25] and MoO 2 (Mo(IV)), commonly present in the distorted rutile structure.…”

“…Such methods include, but are not limited to, spray pyrolysis, [32][33][34] thermal evaporation, 21,35,36 pulsed laser deposition, 37-39 radio frequency magnetron sputtering, 40,41 and reactive DC magnetron sputtering. 9,20,37,42,43 While all of the aforementioned techniques are capable of depositing high quality films when performed under optimal conditions, studies employing reactive DC magnetron sputtering have generated significant interest due to the industrial scalability of magnetron sputtering techniques, as well as the high degree of control over the oxidation state as a function of reactive oxygen availability. 9,20,37,42,43 Previous works of note include studies performed by Mohamed et al demonstrating a comprehensive correlation between oxygen partial pressure and the resulting crystallinity, chemistry, and optical behavior of molybdenum oxide thin films.…”

“…9,20,37,42,43 While all of the aforementioned techniques are capable of depositing high quality films when performed under optimal conditions, studies employing reactive DC magnetron sputtering have generated significant interest due to the industrial scalability of magnetron sputtering techniques, as well as the high degree of control over the oxidation state as a function of reactive oxygen availability. 9,20,37,42,43 Previous works of note include studies performed by Mohamed et al demonstrating a comprehensive correlation between oxygen partial pressure and the resulting crystallinity, chemistry, and optical behavior of molybdenum oxide thin films. 9 While numerous studies have confirmed that it is possible to obtain highquality molybdenum oxide thin films via DC magnetron sputtering, the advent of a technique known as modulated pulse power magnetron sputtering (MPPMS) has shown promise for further optimization.…”