ANNEALING EFFECT ON UV DETECTION PROPERTIES OF ZnO:Al STRUCTURES

Abstract

The aim of this study was to develop low-powered, highly selective UV sensor to continuously monitor personalized UV exposure as well as to study annealing effect on UV detection properties of the sensors. ZnO:Al structures were obtained by chemical growth method followed by thermal annealing at 625 °C for 2 h. The studied samples exhibit maximal UV response of 620/488 at 25 °C/50 °C to 370 nm UV radiation before/after annealing, respectively. Thermal annealing of sensor (250 °C for 1 h) led to improvement in fall time from 3860 seconds to 262 seconds at 25 °C and highest responsivity (~48 mA/W) came out for 370 nm wavelength at 75 °C operating temperatures. Consequently, excellent selectivity for 370 nm UV illumination can be ascribed as due to thermal annealing effect which increases the crystallinity, grain size, and roughness of the sensing film. The PL measurements reveals the suppression of structural defects, increase in intensity after annealing and enhanced UV response due to presence of Al content in films. Overall, these structures showed magnificent UV properties, before and especially after additional thermal annealing. UV sensing mechanism of such nanomaterial-based sensor were explained with physio-chemical processes take place on the surface of these structures. The obtained results on annealed ZnO:Al films-based devices is superior to reported performances of other nanostructures, proving new results for UV sensing applications at different operating temperatures in various fields.

Multifunctional Three-in-One Sensor on t-ZnO for Ultraviolet and VOC Sensing for Bioengineering Applications

“…The high intensity of the ZnO diffraction peaks compared to the background indicates the good crystallinity of the ZnO tetrapod networks. No Zn peaks were observed, showing the complete oxidation of the Zn particles to ZnO during synthesis [ 44 ].…”

“…The whole measurement was carried out in constant voltage mode and the data were acquired by a Keithley 2450. The entire apparatus, shown schematically in Figure 2 , is well established and was fully controlled by specialized software [ 44 ].…”