Impact of high substrate temperature on pulsed laser deposited ZnO pillars: A technological route to investigate the structural, optical and superhydrophilic properties

The structural, optical, and superhydrophilic properties of zinc oxide (ZnO) pillars are reported by pulsed laser deposition (PLD) technique at a high substrate temperature of 700 degrees C. The X-ray diffraction (XRD) analysis reveals that the increased crystallite size in ZnO-700 (98.47 nm) plays an important role in promoting superhydrophilic behaviour than ADZnO-RT (57.19 nm). The root-mean-square surface roughness (Rr.m.s) from scanning probe microscope (SPM) analysis demonstrates the significant enhancement in ZnO-700 surfaces. The ZnO-700 based samples show improved light absorption in the ultra-violet (UV) and visible light absorption which can boost photocatalytic activity. The photoluminescence (PL) analysis shows the highest (zinc) Zn interstitial (Zni) and lowest oxygen vacancy (OV) concentration in ZnO-700. A static contact angle (CA) measurement was performed, where ZnO-700 sample displays a smaller static CA (98.60 degrees) compared to ADZnO-RT (101.90 degrees), indicating more superhydrophilic nature. The ZnO-700 based sample had a better sliding angle (alpha) of 61.65 degrees, a maximum frictional force (Fmax) of 1.76 mu N, a corresponding work of adhesion (Wadhesion) 61.01 mN/m, and a wettability conversion rate (WCR) of 7.20 x 10- 5 degrees- 1/min indicating fast sliding phenomena and better superhydrophilic transition. The superhydrophilic properties of ZnO-700 make it a valuable asset for smart surfaces and microfluidic devices application.

Automated summary

This study investigates the structural, optical, and superhydrophilic properties of zinc oxide pillars prepared by pulsed laser deposition at a high temperature. The results show that the samples prepared at high temperature exhibit larger crystallite size, higher surface roughness, improved light absorption, and enhanced superhydrophilicity. These properties are attributed to the increased interstitial zinc concentration and decreased oxygen vacancy concentration.