Effects of deposition and annealing temperature on atomic layer-deposited tin dioxide thin films

Abstract

Tin dioxide (SnO2) is a promising wide-band-gap n-type semiconductor for transparent conducting oxides (TCOs) and oxide-based electronics. In this work, we investigate the effects of deposition and annealing temperatures on the structural and electrical properties of SnO2 thin films grown by thermal atomic layer deposition (ALD) using tetrakis(dimethylamino)tin (TDMA-Sn) and ozone (O-3). Films were deposited at 150 degrees C and 200 degrees C followed by post-deposition annealing in O-2 between 400 degrees C and 600 degrees C. Crystallographic analysis revealed that higher deposition and annealing temperatures promote rutile phase formation and grain growth, improving carrier concentration and mobility. The optimized sample, which was deposited at 200 degrees C and annealed at 600 degrees C, achieved a carrier density of 2.54 x 10(22) cm(-)(3) and Hall mobility of 51.3 cm(2)/V<middle dot>s, resulting in a low resistivity of 1.89 x 10(-)(4) Omega<middle dot>cm. UV-Vis measurements confirmed high optical transparency (> 80%) in the visible range, supporting TCO applicability. Thickness uniformity and conformality were also demonstrated, achieving step coverage over 96% and wafer-scale thickness uniformity exceeding 98%. While annealing up to 600 degrees C enhanced the film properties, temperatures above 600 degrees C may induce degradation such as interfacial diffusion and grain coarsening. These results highlight that careful optimization of thermal processing conditions enables the fabrication of uniform, highly conductive, and transparent SnO2 films, suitable for next-generation electronic and optoelectronic devices.