Influences of thermal annealing and humidity exposure on surface structureof (100) single-crystal MgO substrate

We studied the influence of thermal annealing on the surface structure of ( 100) single-crystal MgO substrates by atomic force microscopy (AFM). By ann ealing MgO substrates at various temperatures for 4 h in flowing oxygen, we showed that the surface reconstruction could be explained by considering s urface diffusion, surface evaporation, and condensation. At an annealing te mperature of 1473 K, a stepped structure was formed with screw dislocations acting as step sources. The influence of humidity on the surface morpholog y of MgO substrates was also studied by exposing them to a constant humidit y of 40 and 80% for different times, After an exposure time of 1.5 h in 80% humidity, the substrate surface was already covered by reaction products. For the 40% humidity, the corresponding time is 10 h. The major reaction pr oduct was identified as Mg(OH)(2) by x-ray diffraction.