Synthesis and characterization of CrB2 thin films grown by DC magnetron sputtering

Abstract CrBx thin films with 1.90 ≤ x ≤ 2.08 have been deposited by direct-current magnetron sputtering (DCMS) from a stoichiometric CrB2 target at 5 and 20 mTorr (0.67 and 2.67 Pa) Ar pressure onto sapphire (0001) substrates. All films, irrespective of deposition conditions, exhibit a (0001) texture. Attesting to the achievement of close-to-stoichiometric composition, epitaxial film growth is observed at 900°C, while film growth at 500 °C yields (0001) fiber texture. Film composition does not depend on substrate temperature but exhibits slightly reduced B content with increasing pressure for samples deposited at 900°C. Excess B in the overstoichiometric epitaxial CrB2.08 films segregates to form B-rich inclusions. Understoichiometry in CrB1.90 films is accommodated by Cr-rich stacking faults on { 1 1 ¯ 00 } prismatic planes.