Growth and vacuum post-annealing effect on the structural, electrical and optical properties of Sn-doped In2O3 thin films

• Autor(a) principal: Vilca-Huayhua, C. A.
• Data de Publicação: 2020
• Outros Autores: Paz-Corrales, K. J., Aragon, F. F. H., Mathpal, M. C., Villegas-Lelovsky, L. [UNESP], Coaquira, J. A. H., Pacheco-Salazar, D. G.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1016/j.tsf.2020.138207; http://hdl.handle.net/11449/197222
• topic: Vacuum annealing; Indium tin oxide; Band gap energy; Grain size effect; Sheet resistance; Sputtering

Nowadays, the fabrication of cheaper, thermodynamically stable and durable transparent semiconducting oxide-based thin films are on high demand to enhance the properties of optoelectronic, sensing and energy harvesting devices. It is well known that Sn-doped In2O3 (ITO) thin films are difficult to grow by direct current sputtering. However, in this work cost-effective Sn-doped In2O3 films are deposited onto borosilicate glass substrates using a direct current sputtering of metallic In/Sn-target. The film thickness was controlled by the deposition time. A post-deposition annealing of the films in a vacuum atmosphere was performed in order to control the structural, optical and electrical properties. The phase formation, crystallite grain sizes (D) and lattice parameters have been assessed from the X-ray diffraction data analysis. Cross-section Scanning electron microscope image analyses were performed in order to estimate the growth rate of thin films. A band gap energy closing was observed associated with relaxation process of the unit cell suggested by the monotonic reduction of the lattice constant. Besides, a low sheet resistance (44 Ohm/square) was obtained, which is comparable to the commercially available ITO films. Furthermore, a inverse-square dependence between the sheet resistance and the grain size was determined (R-sq similar to 1/D-2). The last was used to estimate the carrier concentration of the thicker film similar to 10(20) cm(-3), which is in agreement with the value obtained from the Hall measurement.