Studies of the electrical properties of the interphase FTO/In2S3 by electrochemical impedance spectroscopy and atomic force microscopy

M. Sanchez-Tizapa1*, M.C. Sosa-Muñiz1, M.A. Carreón-Álvarez1, R. Castañeda-Valderrama1, J.P. Morán-Lázaro2, M. Flores-Martínez3

1Departamento de Ciencias Naturales y Exactas, Centro Universitario de los Valles, Universidad de Guadalajara, Carretera Guadalajara-Ameca Km 45.5, C.P. 46600, Ameca, Jalisco, México

2Departamento de Ciencias Computacionales e Ingeniería, Centro Universitario de los Valles, Universidad de Guadalajara, Carretera Guadalajara-Ameca Km 45.5, C.P. 46600, Ameca, Jalisco, México

3Centro Universitario de Ciencias Exactas e Ingeniería, Universidad de Guadalajara, Blvd. Marcelino García Barragán 1421, Esq. Calzada Olímpica, C.P. 44430, Guadalajara, Jalisco, México.


Keywords: indium tin oxide, thin film, indium sulphide, electrochemical impedance spectroscopy, semiconductor, atomic force microscopy, electrostatic forces, spreading resistance


In this work the study of the electrical properties of the interphase Indium Tin Oxide/Indium Sulphide (ITO/In2S3), by atomic force microscopy and electrochemical impedance spectroscopy is presented. Thin films (~120 nm) of In2S3 were synthesized by electrodeposition. The films were electrodeposited using different complexing agents: 1) sodium citrate; 2) diethylene glycol; and c) acetic acid, the best results were obtained using acetic acid, as thin and uniform films with possibilities of being used as window layer in solar cells were synthesized. The films were characterized by profilometry, X-ray diffraction, energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy and photoelectrochemical reponse. The mapping of the electrical properties of the materials (electrostatic forces, spreading resistance) was done by atomic force microscopy. The measurement of the mismatch between work functions of ITO and In2S3 resulted in ~1 eV, according to previous reports. X-ray diffraction showed a mix of tetragonal and cubic phases, by X-ray spectroscopy it was observed that stoichiometric films were synthesized. Electrochemical impedance spectroscopy probed to be useful as it was the only technique capable of detecting and analyzing thin films of In2S3, that no other technique could detect. Mott Schottky characterization and photoelectrochemical response showed the characteristic behavior of an n-type material.


Summary of academic career

Prof. Marciano Sánchez Tizapa studied at the Chemical Engineer from the Universidad Autónoma del Estado de Morelos, México (1998), Master (2006) and PhD (2010) from the Universidad Nacional Autónomade México. Graduated with honors by the Master and PhD Thesis and nominated to the Alfonso Caso Medal awarded to the best Master and PhD Thesis at the Universidad Nacional Autónoma de México, he was also awarded with the First Prize in the XIX National Contest of BS Thesis by the Instituto de Investigaciones Eléctricas, México. Dr. Sánchez has synthesized and characterized cadmiun sulphide, cadmium selenide and titanium dioxide for solar cells, he has also developed composite materials based on carbon nanotubes-titanium dioxide for gas sensors, he has knowledge about several semiconductor synthesis and characterization techniques, Sol-Gel, chemical bath deposition, electrodeposition, thermal evaporation, conductimetry measurements in DC current, photolectrochemical cells, X-ray difraction, atomic force microscopy, electrochemical impedance spectroscopy, zeta potential and particle size measurements by dynamic light scattering. Has published 4 books, 8 book chapters, 16 research papers, and has participated in 35 national and international meetings. Actually is working at the Centro Universitario de los Valles of the Universidad de Guadalajara, where he has colaborated to the design and implementation of Electronic Instrumentation and Nanosensors Engineering. Actual research topics are the elaboration of new semiconductors for solar cells and gas sensing as well as water remediation. He has colaborated in two projects funded by Consejo Nacional de Ciencia y Tecnología and Secretaría de Educación Pública of México, and actually is leading two projects funded by the Consejo Nacional de Ciencia y Tecnología and the Centro Universitario de los Valles de la Universidad de Guadalajara.