Low-temperature growth of MgO by molecular-beam epitaxy

We have explored the epitaxial growth of MgO single crystals using separate O₂ and Mg beams and also e-beam-evaporated MgO. The latter method is preferred as the incorporation efficiency of O₂ turns out to be {~}10^-3 even at 200 ^∘{}C in the former method. Excellent MgO grows by e-beam evaporation at temperatures down to 140 K (Tₘ/20), in agreement with expectations of Yang and Flynn. Good surface quality is achieved in heteroepitaxy, even for the first few monolayers.