STRUCTURE OF EPITAXIAL OVERGROWTHS OF CU2S FORMED ON (111) CU

Overgrowths of Cu2S were formed on (111) single-crystal films of copper by exposing them to sulfur vapor in the temperature range 25-300 °C. Reflection high energy electron diffraction (RHEED) analysis revealed that the resultant overgrowths were epitaxial and of various structural forms depending predominantly on the duration of exposure and not on the temperature. The overgrowth started as a cubic form of Cu2S but transformed to the hexagonal form and finally to the orthorhombic form. The morphology of the Cu2S indicated by RHEED, scanning electron microscopy and transmission electron microscopy proceeds from a smooth flat structure to an island-type formation. © 1979.