Phase modulation of MoO2 -MoO3 nanostructured thin films through W-Doping; utilizing UV photodetection and gas sensing applications

Gas sensing properties of metal oxide semiconductors draw high attention due to their simple fabricating methods, and low cost, chemical, and physical properties. In general, a high bandgap (>2 eV) can cause them to react in the UV region through the electromagnetic spectrum. Controlling the UV-photodetection and gas sensing ability of MoO2-MoO3 thin film through tungsten (W) doping of different ratios have been reported here. The preparation of these films was grown using a reactive magnetron sputtering system with different power sputtering of W-content. The bandgap calculations showed that the samples have a wide bandgap value. A small particle size of 8nm was observed through high W doping concentration which enhanced these materials toward high efficient gas sensing and UV photodetector applications. The UV optical sensor exhibits a high responsivity value of 2500A/W and an external quantum efficiency (EQE) value of 5x109 at 365nm. Also, an increase in the photocurrent gain value with increasing the W amount with a maximum value of 0.13, while a photocurrent of 1mA was observed. On the other hand, a fast-response/recovery time-based CO2 gas sensor of less than 10 sec was observed. The thin-film sensors showed well-defined adsorption and desorption kinetics in a CO2 environment with a p-type chemisorption behavior.