Effect of annealing temperature on the thermal transformation to cobalt oxide of thin films obtained via chemical solution deposition. (1st March 2020)

• Record Type: Journal Article
• Authors: Martínez-Gil, M.; Cabrera-German, D.; Pintor-Monroy, M.I.; García-Valenzuela, J.A.; Cota-Leal, M.; De la Cruz, W.; Quevedo-Lopez, M.A.; Pérez-Salas, R.; Sotelo-Lerma, M.
• Is Part Of: Materials science in semiconductor processing. Volume 107(2020)
• Publication Date: 2020-03-01
• Subjects: Thin films -- Spinel cobalt oxide -- p-type -- XPS -- Band diagram -- Chemical solution deposition; Semiconductors -- Periodicals; Integrated circuits -- Materials -- Periodicals; Semiconducteurs -- Périodiques; Circuits intégrés -- Matériaux -- Périodiques; Electronic journals; 621.38152
• DOI: 10.1016/j.mssp.2019.104825
• Languages: English
• ISSNs: 1369-8001

Abstract

Abstract: An ammonia-free chemical solution deposition formulation is employed to synthesize cobalt hydroxide thin films. The films are subsequently annealed at different temperatures to obtain cobalt oxide (Co3 O4 ). The reaction solution is composed solely of cobalt sulfate and triethanolamine. The annealing temperature has a strong effect on the properties of thin films. X-ray diffraction shows that the films are amorphous despite the thermal treatment; the morphology for both as-deposited and annealed films are found to be homogeneous, compact, with no evident changes. X-ray photoelectron spectroscopy reveals that the as-deposited thin films are mainly composed of cobalt hydroxide. After annealing, the films transform into cobalt oxide (Co3 O4 ) thin films. The optical spectra confirm the X-ray photoelectron spectra, due to the appearance of characteristic features of Co3 O4 on both characterization methods. The energy band gap is estimated to lie between 2.1 and 3.0 eV. The resistivity of the annealed films ranges from 4.29 × 10 3 to 1.46 × 10 4 Ω⋅ cm. Finally, with the work function and ionization energy, we propose an experimental band diagram as a function of annealing temperature, showing a p -type nature for the cobalt oxide films.