OBSERVATION OF 1-NM-HIGH STRUCTURES ON A SI(001) SURFACE USING A DIFFERENTIAL INTERFERENCE OPTICAL MICROSCOPE

A Si(001) clean surface is oxidized by exposure to air and the step-ba nd structures on the oxidized surface are observed using a differentia l interference optical microscope in air. The step-bands observed cons ist of many monatomic steps. Electromigration, induced using alternati ng-current heating, splits the step-band into steps on the Si(001) sur face. The number of monatomic steps is counted after alternating-curre nt heating and the height of the step-band is determined to he about 1 nm. Using a differential interference microscope, it is possible to o bserve structures with height of nanometer-order on a Si(001) surface.