Deep level transient spectroscopy studies on BaTiO3and Ba1–xCaxTiO3thin films deposited on Si substrates

Laser ablation grown BaTiO3 and Ba1-xCaxTiO3 thin films were studied in the metal-ferroelectric-semiconductor configuration by the deep level transient spectroscopy (DLTS) technique. The capture cross section, bulk and interface traps were determined from the DLTS technique. The distributions of calculated interface states were mapped with the silicon energy band gap for both the thin films. The interface states of the Ba1-xCaxTiO3 thin films were found to be higher than the BaTiO3 thin films. The substitution of Ca2+ into the Ba2+ sites of BaTiO3 results in a decreased lattice constant, thereby leading to shrinkage in the unit cell. This might be one of the reasons for the higher density of interface states present in Ba1-xCaxTiO3, as it leads to a large number of unsaturated bonds at the interface of Si substrate-thin films. The calculated capture cross section of the interface traps in both the BaTiO3 and Ba1-xCaxTiO3 thin films was very low in the range of 10(-21) cm(2).