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

Abstract

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.

The versatile family of molybdenum oxides: synthesis, properties, and recent applications

“…Both works demonstrate the possibility of manufacturing optoelectronic devices beyond the diffraction limit. In the UV range, Zaki et al [114] report W-doped MoO 2 -MoO 3 thin films with long-term stability as a UV PD, modifying the optical bandgap with the W composition (in the range 3.31-3.97 eV). Wu et al [115] fabricated UV PD devices by annealing MoO 3 ribbons, reducing them to MoO 2 and thus forming MoO 2 /MoO 3 heterostructures.…”

Thermionic Emission of Atomic Layer Deposited MoO3/Si UV Photodetectors

“…Because a 5 V bias gave the sample more activations for better photoconductivity and a better photodetector response, we calculated the photocurrent gain, photoresponsivity ( ), external quantum efficiency (EQE), detectivity ( ), and finally the response/recovery time at 5 V biase. The calculations were collected based on the previous reports [ 54 , 55 , 56 ]. For a UV photodetector, the responsivity is important as it is a measure of the sensitivity of a photodetector to light.…”

Optical, Optoelectronic, and Third‐Order Nonlinear Photonics of Ultrathin Molybdenum Oxide Film Deposited by Atomic Layer Deposition

“…[ 1,2 ] Molybdenum oxides (MoO x ) have gained a lot of attention as transition metal oxides because of their electron affinity, broad bandgap, various valence states, and layered structure and could be used in sensors, optics, catalysis, electronics, energy units, and biosystems. Recently, MoO 3 is a popular high‐ k transition metal oxide that has been used in a variety of applications such as gas sensors, [ 3,4 ] heterogeneous catalysis, [ 5 ] super‐capacitance, [ 6 ] and ion batteries, [ 7 ] and photovoltaics. [ 8 ] To increase the efficiency of organic light‐emitting diode (OLED) devices, thin films of molybdenum trioxide have been explored in the charge‐generating layer in OLEDs as an injection layer and a synthetic metal anode/cathode.…”