Controlled optoelectronic properties and abrupt change in photosensitivity by suppressing density of oxygen vacancies in SnO₂ nanocrystalline thin films prepared at various spray-deposition temperatures

Abstract

Nanostructured SnO2 thin films were synthesized at various substrate temperatures using a modified chemical spray pyrolysis (MCSP) technique. The x-ray diffraction (XRD) patterns confirmed the presence of a rutile SnO2 with tetragonal structure for all the resultant film samples. The XRD results ascertained increase in the grain growth rate and consequent enhancement in crystallinity with increasing the spray-deposition temperature. The optical spectroscopic analysis revealed a significant increase in the optical transmission within the visible region as well as a considerable increase in the optical bandgap by increasing the deposition temperature. However, the spectral distribution of the absorption coefficient ascertained the dominance of direct allowed transition for the SnO2 film samples. The analysis of the current-voltage characteristic curves revealed that the variation of the spray-deposition temperature strongly influences the photosensitivity of the film samples. Based on the electrical results, these film samples reveal a semiconductor behaviour of the transport property over the entire investigated range of the working temperature, with two different conduction mechanisms. The optical and electrical results were combined to evaluate the influence of varying the deposition temperature on the figure of merit (FOM) factor for the SnO2 film samples.

Hydrothermal Synthesis and Characterization of SnO₂ Nanosheets

“…Nowadays, nano-forms of SnO2 replace the bulk forms to increase the high surface to volume ratio as well as enhance the depletion layers, which play a key factor in their sensitivity. To synthesis SnO2 with nanostructure forms, many methods have been introduced to obtain different structures including: chemical vapour deposition CVD [8], sol-gel [9], spry deposition [10], and hydrothermal methods [11][12][13]. Among them, the hydrothermal method has become the easiest way to synthesis nanostructure materials with numerous structures.…”