Growth of MgO from the vapor phase onto single−crystal metal substrate

Abstract

The growth of MgO films (∠30−4000 Å) deposited from the vapor phase on atomically smooth (111) surfaces of silver single−crystal film substrates has been studied by reflection high−energy electron diffraction. At substrate temperatures between 30 and 150°C, thin films (∠30 Å) are oriented with their (111) planes parallel to the (111) silver surface and with the [11̄10] and [̄110] MgO directions parallel to the [11̄0] silver direction. At and above 150−160°C, the orientation changes from a (111) plane to a (100) plane parallel to the (111) silver surface. The (100) orientation is fibrous with a preference for the [110] MgO direction to be parallel to the [11̄0̄] silver direction. The angular position of the (111) and (100) planes is consistent with best atomic matching at the interface between the deposit and substrate. As the film thickness is increased, the surface orientation changes to 1° (111) independent of substrate temperature. The axis of the (111) orientation tilts away from the substrate normal and toward the vapor beam direction at oblique vapor incidence.