Stoichiometric, epitaxial ZrB2 thin films with low oxygen-content deposited by magnetron sputtering from a compound target: Effects of deposition temperature and sputtering power

• DCMS of stoichiometric and epitaxial ZrB2 thin films with low oxygen-content.
• Epitaxial growth is favored by high sputtering power and high growth temperature.
• The film growth mode changes from fiber textured to epitaxial above 820 °C.
• Low sputtering power of 100 W yields increased surface roughness and porosity.
• The oxygen content scales with the sputtering power and influences film resistivity.

Zirconium diboride (ZrB2) thin films have been deposited on 4H-SiC(0001) substrates by direct current magnetron sputtering from a compound target. The effect of deposition temperature (500-900 °C) and sputtering power (100-400 W) on the composition and structure of the films have been investigated. Electron microscopy and X-ray diffraction reveal that high sputtering power values and high deposition temperatures are favorable to enhance the crystalline order of the epitaxial 0001-oriented films. X-ray photoelectron spectroscopy shows that the composition of the films is near-stoichiometric for all deposition temperatures and for high sputtering power values of 300 W and 400 W, whereas understoichiometric films are obtained when applying 100 W or 200 W. Decreasing the deposition temperature, or in particular the sputtering power, result in higher C and O impurity levels. The resistivity of the films was evaluated by four-point-probe measurements and found to scale with the amount of O impurities in the films. The lowest resistivity value obtained is 130 µΩ cm, which makes the ZrB2 films interesting as an electrical contact material.