Tuning the charge carrier density in TiO2 films

M. VALDÉS; I. JURICH; M. VÁZQUEZ

Joao Pessoa

Congreso; VIII Congreso de la Sociedade Brasileira de Pesquisa em Materiais (SBPMat); 2014

Sociedade Brasileira de Pesquisa em Materiais (SBPMat)

Titanium oxide (TiO2) is a material with high chemical stability. Given its adequate properties, it is an ideal material for applications in optoelectronic devices, particularly in the field of photovoltaic cells [1]. TiO2 is an n-type oxide semiconductor due to the presence of oxygen vacancies in the crystal lattice. The generation or passivation of oxygen vacancies can alter the density of charge carriers and thereby determine the electrical response of the material. The carrier density can also be tuned by doping the material with another element. For this purpose, varying amounts of Sn was used in this work. In this work pure anatase TiO2 thin films were prepared using spray pyrolysis. The films were deposited on conducting FTO (Fluorine Tin Oxide) glass substrates from an alcoholic solution, acetylacetone and titanium isopropoxide as a source of titanium and dispersant, respectively. Subsequently, the films were thermally treated at different temperatures and under a controlled atmosphere, in order to modify the charge carrier density ND. For the electrical characterization Schottky barriers were formed by depositing a graphite contact on top of the TiO2 films. The Schottky barriers were characterized by current-voltage curves (I-V). Capacitance-Voltage measurements were also performed in order to calculate the carrier density ND, following the Mott-Schottky equation. The carrier density increases after annealing in vacuum.