Experimental details
High-density plasma obtained from a Cr target (99.999% pure;
4 in. in diameter) in an atmosphere of C2H2 can be achieved using
a FCVA in this work. P-type (1 0 0) silicon wafer with dimensions of
20 mm × 20 mm was ultrasonicated in acetone and then in alcohol
for 15 min and finally loaded in a substrate holder. Prior to coating,
the substrate surfaces were activated by argon bombardment
for 5 min at a pressure of 1.29 Pa and a substrate bias voltage of
−950 V to remove various possible native oxides. Then the substrate
holder was heated by a hot plate with a thermocouple
nearby to monitor the substrate temperature