Atomically flat MgO single-crystal surface prepared by oxygen thermal annealing

Single-crystal MgO is a good candidate substrate for growing metal oxide fi lms, even though it has a few drawbacks, such as surface degradation caused by its easy reaction with H2O and CO2 and high concentration of impurities originating from the method by which it is grown. We propose a thermal ann ealing carried out under novel conditions. 700 degreesC and 1 atm O-2 atmos phere, for resolving these drawbacks. An atomically flat surface with a hal f-unit-cell-high step-and-terrace feature was realized on a MgO(100) substr ate with a reduced surface segregation of impurities.