Figure 2: RHEED comparison for CaO growth in oxygen and water vapour.
From: Surfactant-enabled epitaxy through control of growth mode with chemical boundary conditions

RHEED data for 〈111〉 CaO epitaxial films prepared on [0001] GaN. (a) Corresponds to a film grown in molecular oxygen whereas (b) corresponds to a film grown in an equivalent flux of water vapour. All other deposition conditions are identical. The intensity vs. time plots are collected from the specular reflection.