Investigation of surface and interface properties of RF sputtered calcium copper titanate thin films on silicon substrate

Abstract

Structural and electrical properties of RF sputtered Calcium copper titanate (CCTO) thin films have been investigated. CCTO thin films were sputtered on p-type silicon (100) substrate by varying deposition pressure from 2.5 × 10^-3 to 1 × 10^-2 mbar without using platinum buffer layer. Post deposition annealing of all the samples were carried out at 950 °C. A correlation between morphological and electrical properties of the CCTO films was established with the variation of deposition pressure. The evolution of polycrystalline structure of the CCTO thin films was confirmed by XRD studies. The characteristic FTIR absorption peaks in the range of 400–700 cm^-1 depicted the formation of CCTO for all the samples. The films grown at higher pressure have irregular grains with the evolution of (310) peak. Electrical properties of the dielectric films were investigated by fabricating Al/CCTO/Si metal oxide semiconductor structure. The electrical properties of the CCTO films were found to be deteriorated at higher sputtering pressure. Thin films, deposited at 5 × 10^-3 mbar, possess higher dielectric constant, lower charge density and also lower leakage current.