Properties of TiC thin films grown by pulsed laser deposition

Titanium carbide thin films have been deposited on both (100) silicon and fused silica substrates by pulsed laser ablating a polycrystalline TiC target. At a KrF excimer laser intensity of about 8 x 10(8) W/cm(2), the pulsed laser deposition (PLD) of TiC films was investigated at substrate deposition temperatures ranging from 25 to 600 degrees C. The structure, surface composition, electrical resistivity, stress, work function and morphology of the PLD TiC films were characterized as a function of the deposition temperature. While all the deposited TiC films are polycrystalline with a preferred (111) orientation, both the magnitude of their compressive stress and their resistivity were found to decrease gradually as a function of the deposition temperature, from -7 to similar to-3 GPa and from 140 to 80 mu Omega cm, respectively. The X-ray photoelectron spectroscopy (XPS) analysis revealed that oxygen (at an average level of similar to 10 at.%) is incorporated into the TiC films where it substitutes for C. The surface composition of the films is found to be stoichiometric with an average Ti/(C + O) ratio of 0.98 +/- 0.06. The deposited TiC films exhibited low work functions in the (3.74-3.94) eV range. Their surface morphology is characterized by a very smooth surface on which some particulates are present. The density of these particulates (of which typical lateral dimension is about 1 mu m and height is about 100 nm) is of the order of 2 per 100 mu m(2). The properties of these PLD TiC films are discussed in view of their use as electron injecting electrode materials for organic electroluminescent devices. (C) 1999 Elsevier Science B.V. All rights reserved.