Laser-induced periodic surface structures on ZnO thin film for high response NO2 detection

Abstract

Femtosecond laser-induced periodic structures (LIPSS) have been processed on ZnO thin film gas sensor devices for nitrogen dioxide (NOi) detection. From the morphology point of view, the nanostructures have been iden tified as high spatial frequency UPSS (HSFL) with an average period of 145 nm. Through Raman analysis, a decrease of the typical wurtzite ZnO structure is shown, with a possible increase of defects such as Zn inter sti tials. The response under N(½ is enhanced if compared with the only-annealed ZnO thin film for conoentra tions as low as 1 ppm, reaching 1 ppb of detection lirnit (WD) for the sensors with LIPSS. The Zn interstitials defects could be the source of the adsorbed N(½ species increasing the sensitivity. Reproducible results have been measured during 11 weeks in a row.

Low-temperature operating ZnO-based NO2 sensors: a review

“…When the sensor is exposed to the oxidizing gas such as NO 2 , the gas molecules will not only capture the electrons in the conduction band of ZnO, but also interact with the oxygen species adsorbed on the surface of ZnO, resulting in an increase in the width of the electron depletion layer and junction potential barriers, which will increase the resistance of sensor and generate sensing response (eqn ( 5)-( 7)). [59][60][61] When the sensor is exposed to air again, NO 2 À reacts with the holes and releases the electrons back to the conduction band, causing NO 2 to be released into the air and reducing the resistance (eqn ( 8)). Fig.…”

Low temperature NO2 gas sensing with ZnO nanostructured by laser interference lithography

“…They analyse the ZnO by Raman spectroscopy, revealing a decrease of the ZnO wurtzite structure and an increase of the surface defects such as Zn interstitials. 45 Regarding the analysis of both works, the results that have been obtained in this work could indicate that a higher number of surface defects are obtained by processing the material with laser interference. On the other hand, vertically oriented ZnO nanomaterials have been proved benecial for gas sensing.…”

Picosecond Laser Interference Patterning of Periodical Micro-Architectures on Metallic Molds for Hot Embossing

“…LIPSS [65,66,67,68], a universal phenomenon that occurs after laser irradiation on a wide number of different materials [69,70,71], have been found to exhibit different characteristic shapes, including ripples (lines), rods, cones, grooves, etc. The generation of LIPSS takes place commonly only in a fluence range close to the material damage threshold and even just below the ablation threshold [72].…”