Engineering epitaxial-nanospiral metal films using dynamic oblique angle deposition

Using dynamic oblique angle deposition with substrate rotation, we showed that single crystal porous Cu(100) films in the form of spirals with an arm diameter ranging from 20 to 50 nm and a spiral diameter ranging from 100 to 150 nm can be epitaxially grown on hydrogen terminated single crystal Si(100) substrate. The epitaxial relationships are (100)_Cu//(100) _Si in the out-of-plane orientation and [010]_Cu//[011] _Si in the in-plane orientation. The X-ray pole figure shows that the epitaxial Cu spirals possess symmetric and weak twins, in contrast to the asymmetric and strong twins observed in slanted nanorods deposited on Si(100) under stationary oblique angle deposition. These films have potential applications in sensors, catalysts, and energy conversion devices.